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Saturday, 27 June 2015

Flammable Refrigerants

Flammable Refrigerants To Be Taken Care Of 


flammable refrigerant caused car fire


Flammable refrigerants are illegal to use in an automotive air conditioning system. There are some exceptions, such as the new R1234yf refrigerant, which is mildly flammable but only under certain conditions. Flammable refrigerants may also be used in the trailer refrigeration units on heavy duty trucks. But other than these, no flammable refrigerant should ever be used in a car or light truck A/C system.

Flammable Refrigerant Fire Hazards

Propane, butane and a number of other hydrocarbon mixtures and blends actually work quite well as refrigerants, with cooling characteristics similar to R-12, R-22 and R-134a. But if the evaporator inside the passenger compartment develops a leak, the flammable vapor may create a potential for a fire or explosion. Do you really want to risk being cremated while driving your vehicle?
Another thought to keep in mind is what happens if your vehicle is involved in an accident. The A/C condenser sits right in front of the radiator and contains high pressure refrigerant vapor and liquid. If the condenser is ruptured in a frontal collision (which it often is), high pressure flammable vapor will be released, almost guaranteeing an underhood fire!
Do you really want to risk your life or the lives of your passengers by using a cheap flammable refrigerant in your vehicle's air conditioning system? R-134a is the only refrigerant that should be used when recharging a late model automotive A/C system.

EPA SNAP Rules on Flammable Refrigerants

The US EPA SNAP regulations do NOT allow the use of flammable refrigerants in vehicles.
The only exception is a new refrigerant called HFO-1234yf which is only mildly flammable under certain conditions. For info on EPA SNAP regulations, see this link:
The Mobile Air Conditioning Society (MACS) also does NOT approve of using flammable refrigerants. Nor does the Society of Automotive Engineers (SAE). Like the EPA SNAP rules, the only exception is the new HFO-1234yf refrigerant that will start appearing in some new cars in 2013 or beyond as a replacement for R-134a.

Use R-134a Only

The EPA, MACS and SAE all say that the only acceptable replacement refrigerant for newer R-134a system is R-134a. Nothing else should be used to avoid cross-contamination problems and cooling performance issues. Older vehicles with R-12 can be retrofitted with R-134a or other approved alternative refrigerants (which also must NOT be flammable).
Here is document that contains a lot of good information about alternative refrigerants, though it is dated 1999. The basic information is unchanged, and the only update would be the approval of HFO-1234YF for future A/C systems.
Flammable Refrigerants are Against the Law!
Many city municipalities and states have laws prohibiting the use of flammable refrigerants in vehicles.
In Europe, propane is allowed in some home refrigerators, but the amount is so small that it poses no explosion or fire hazard. Refrigerators must also pass safety tests that show any refrigerant leak cannot create a fire or explosion hazard.

Flammable Refrigerants: OZ-12 and HC-12A

Alternative refrigerants that do not meet the EPA's criteria for environmental acceptability or safety include OZ-12, HC-12a, R-176 and R-405a. Flammable refrigerants such as OZ-12 and HC-12a contain large quantities of hydrocarbons (propane, butane, isobutane, etc.) and have been declared illegal for use in mobile A/C applications but are still finding their way into A/C systems because of their cheap price.
The EPA does not approve of flammable refrigerants because the EPA says they pose a significant danger to a vehicle's occupants should a leak occur. The EPA says a spark from a cigarette or a switch could ignite leaking refrigerant causing an explosion and fire.
Counterpoint: The makers of HC-12a contend that the flammability danger is highly exaggerated and there is "no evidence" to support claims that a cigarette or spark can ignite their product. They also contend that the EPA's position on their product is unfair, and that HC-12a has been successfully used in many vehicle A/C systems worldwide with no accidents or injuries due to ignition.

HFC-152a

Another alternative refrigerant that has been proposed for automotive use is HFC-152a. It has a GWP rating of 140, which meets the European requirements for combating global warming. HFC-152a has cooling characteristics very close to that of R-134a, and could probably be used as a direct substitute for R-134a with few if any modifications. But HFC-152a is flammable, so it is currently illegal to use.
One possible solution to the flammability issue HFC-152a (or other flammable refrigerants) is to add a leak sensor inside the vehicle that warns the passengers if a leak occurs, and automatically opens the power windows to vent the vapors (thus, reducing the fire/explosion risk).
Another solution is to redesign the A/C system so that it uses a "secondary loop" to keep the flammable refrigerant in the engine compartment and out of the passenger compartment. With this approach, the refrigerant circulates through an intermediate heat exchanger and chills a liquid (probably a water/antifreeze mixture) that then flows through the HVAC unit inside the vehicle. A recent report from the U.S. EPA says this approach meets its safety criteria, while also being energy efficient. But it does not reduce the risk of fire in a frontal collision, and it still poses a risk to technicians and do-it-yourselfers while recharging or servicing the A/C system.

HFO-1234YF

The newest alternative refrigerant is HFO-1234yf. The refrigerant replaced R-134a in model year 2014 on a few vehicles. It has thermal characteristics that are similar to R-134a, so only minor modifications to the A/C system are necessary (larger condenser and different PAG oil). It has a low GWP rating of only 4, which meets the European requirements for reducing global warming. But it is mildly flammable (though much less so than HFC-152a) and will only burn under certain conditions which should NOT occur in normal automotive usage.
For more information about HFO-1234YF, see 1234facts.com.

Update: November 2012

Volkswagen says it will NOT use HFO-1234yf Refrigerant because of Safety Concerns

Citing concerns that the alternative refrigerant HFO-1234yf can burn in real life conditions inside a vehicle, Volkswagen said that it will NOT switch its vehicles to HFO-1234yf. At this time, it appears that CO2 is the best alternative to R-134a, according to VW. This decision follows a similar announcement late last month by Daimler (Mercedes Benz) to abandon work on HFO-1234yf in favor of CO2 or other alternative refrigerants.
HFO-1234yf can by ignited by a spark within seconds of its release, and emits highly toxic fumes and acids as it burns according to tests conducted by Daimler. CO2 is nonflammable and is carbon neutral, so it appears for now that HFO-1234yf is on hold as far as two of the leading German auto makers are concerned.

Update: June 26, 2013

SAE says HFO-1234yf is Safe for Use in Passenger Car A/C Systems

After extensive testing and review, SAE International has concluded that Honeywell's new HFO-1234yf low-global-warming-potential mobile air conditioning refrigerant is safe for use in automobiles. Yes, it can be flammable under certain conditions, but those conditions are highly unlikely to occur in a real world crash, concludes SAE.
To read the official press release, Click Here.



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R-1234yf Refrigerant

R-1234yf Refrigerant For Your Car


Auto makers are slowly moving toward a new refrigerant for automotive air conditioning systems. The new refrigerant is R-1234yf (HFO-1234yf), and it will be phased in slowly over time starting with some 2014 model year vehicles.
R-1234yf has cooling properties that are similar to R-134a, which has been used as an automotive refrigerant since it was introduced back in 1994 to 1995 to replace R-12. R-134a contains no CFCs, which are harmful to the Earth’s protective ozone layer, but it does retain heat well and has a relatively high Global Warming Potential (GWP) rating of 1410.

IMPACT ON GLOBAL WARMING


Automotive refrigerants that leak out of A/C systems contribute very little to the overall global warming problem, only about 0.14% according to scientific estimates. Even so, when you multiply the millions of vehicles that are AC-equipped times even a small amount of refrigerant leakage over time, the numbers can add up. Some would argue that switching to a new refrigerant is unnecessary and will hardly make a dent in climate change. Others argue that it is all a conspiracy by DuPont and Honeywell to monopolize the world automotive refrigerant market by getting regulators to require a new low global warming potential refrigerant. R-1234yf has a GWP rating of 4, which is over 350X less than R-134a!
Politics and conspiracy theories aside, regulations have already been passed in Europe that will require some type of new refrigerant. The Europeans were considering CO2 (R-744) because it has the lowest GWP rating of all: One! But A/C systems that operate using CO2 require extremely high pressures (1,800 to 2,200 PSI versus 300 to 400 PSI for R-134a and R-1234yf) and are much more expensive to manufacture.
The auto makers had agreed on moving ahead with R-1234yf until Daimler (Mercedes-Benz) ran some tests that revealed R-1234yf could ignite under certain special conditions. Based on the test findings, Mercedes and Volkswagen said no to the new refrigerant. R-1234yf is slightly flammable, but according to the Society of Automotive Engineers (SAE), the new refrigerant is safe for automotive passenger car use. The risk of fire is extremely remote in case of an accident or refrigerant leak into the passenger compartment.
To read the official SAE press release, Click Here.
hfo-1234yf refrigerant cooling performance chart .

HOW DOES R-1234YF COMPARE TO R-134A?

R-1234yf has cooling performance that is similar to R-134a but not quite as good. It is about 5 percent less efficient than R-134a. It is not a simple drop-in substitute for R-134a because it requires a slightly larger or more efficient condenser and a more robust leak-resistant evaporator (for safety). R-1234yf also requires a new type of compressor PAG oil, as well as new J2843 certified recovery and recycling equipment designed especially for the new refrigerant. And here’s the punch line: R-1234yf is significantly more expensive than R-134a ($120 per pound versus about $10 per pound).
Other hydrocarbon and hydrocarbon-blend refrigerants (such as propane, butane and others) have also been considered, but would require some type of secondary loop cooling configuration and special safety features to keep the potentially explosive vapors away from the passenger compartment. Many states ban the use of flammable refrigerants in motor vehicles (except for use in refrigerated truck trailer cooling units).

R-134A WILL CONTINUE FOR CURRENT VEHICLES AND OLDER VEHICLES

As of this writing, there are no plans to eliminate R-134a as happened to R-12, or to require retrofitting older vehicles or current vehicles that have R-134a A/C systems to the new HFO-1234yf refrigerant. R-134a will remain in production to service existing A/C systems.
R-134a should only be used in R-134a systems, and should NOT be used to top off a R-1234yf system. Likewise, R-1234yf should NOT be used in an older R-134a or R-12 A/C system due to material compatibility and lubrication issues.
R-1234yf A/C systems will have their own unique service fittings (which are different from R-12 and R-134 fittings) to discourage accidental cross-contamination.

R-1234YF SERVICE PRECAUTIONS

Because R-1234yf is slightly flammable, an evaporator that is leaking MUST be replaced with a new unit. The installation of a used evaporator from a salvage vehicle is NOT allowed because there is a chance it might also leak, exposing the vehicle's occupants to potentially flammable vapor mixture.
Professional service equipment for R-1234yf includes a leak check feature built into the recovery and recharging machine. The equipment also includes a refrigerant identifier to make sure the vehicle's A/C system contains R-1234yf and not some other refrigerant.
If your a/C system is leaking, the leak MUST be fixed before the shop will recharge your A/C system with refrigerant.

R-1234yf NEW CAR APPLICATIONS

The first U.S. vehicle to use R-1234yf refrigerant was the 2013 Cadillac XTS. Cadillac also tried R-1234yf in the Cadillac ATS, but stopped only one month into production because of A/C compressor noise and vibration issues. Early production ATS models were recalled and retrofitted back to R-134a (which apparently works fine in an A/C system designed for R-1234yf).
For model year 2014, R-1234yf is used in the Jeep Cherokee, Chrysler 300, Dodge Ram 1500, and Dodge Charger, Challenger and Dart. It will also be used in the 2015 Chrysler 200.
Most auto makers are expected to have numerous R-1234yf applications by model year 2017 and beyond. Auto makers receive fuel economy credits for vehicles that are converted to R-1234yf, which helps them achieve the new higher Corporate Average Fuel Economy (CAFE) requirements.
Update February 2015

R-1234yf Vehicle Applications:

Here is a list of late model vehicles sold in North America that are using R-1234yf refrigerant in their air conditioning systems:

BMW i3 Electric
Cadillac XTS (2013 and 2014)
Chevrolet Malibu
Chevrolet Spark EV (2014)
Chevrolet Trax
Chrysler 300 (2014)
Dodge Challenger (2014)
, Honda Fit EV (2013 and 2014)
Hyundai Santa Fe & i30
Ford Transit
Infinity Q50
Jeep Cherokee (2014)
Kia Sorento, Optima & Cadenza
Mazda CX-5
Mitsubishi Mirage
Range Rover and Range Rover Sport (2014)
Subaru BRZ, Forrester & Impreza


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Alternative Refrigerants

Alternative Refrigerants For Your Vehicle 


R12 refrigerant

As R-12 continues to disappear, the price of R-12 refrigerant continues to rise. So what do you recharge an older air conditioning system with if R-12 is unavailable?

DROP-IN ALTERNATIVES FOR R-12 REFRIGERANT?

Though a number of alternative refrigerants are marketed as "drop-in" replacements for R-12, there is really no such thing as a true drop-in replacement. The reason why is because Federal law prohibits the topping off A/C systems with ANY refrigerant that is chemically different from what is already in the system, unless all of the old refrigerant is first removed so the system can be converted to the alternative refrigerant.
There are, however, a number of alternative refrigerants that can be used in older vehicles with R-12 A/C systems, and most have been reviewed and approved by the EPA for retrofitting older R-12 A/C systems. Approved refrigerants must meet the EPA's SNAP (Significant New Alternatives Policy) criteria for environmental acceptability and usage.
NOTE: The SNAP rules prohibit the use of flammable refrigerants (propane, butane and similar hydrocarbons) in mobile A/C systems because of their hazardous nature, and the SNAP rules prohibit the use of any other refrigerants that contain ozone-damaging CFCs. for more information about flammable refrigerants, Click Here.

APPROVED ALTERNATIVE REFRIGERANTS

There are number of alternative refrigerants from which to choose. One is R-134a, which is the ONLY alternative refrigerant currently approved by all vehicle manufacturers for retrofitting older R-12 A/C systems. The vehicle manufacturers say R-134a will cool reasonably well in most R-12 A/C systems provided the proper retrofit procedures are followed. They also recommend R-134a because it is a single component refrigerant, unlike most of the alternatives which are actually BLENDS of two to more ingredients.
The vehicle manufacturers do not like blends because blends can undergo "fractionation." This is when the individual ingredients in a blend separate for various reasons. Fractionation can be caused by chemical differences between the refrigerants (lighter and heavier elements do not want to stay mixed), different rates of leakage through seals and hoses (smaller molecules leak at a higher rate than larger ones), and different rates of absorption by the compressor oil and desiccant. Fractionation is a concern because it can change the overall composition of the blend once it is in use, which can affect the performance characteristics of the refrigerant. Fractionation also makes it difficult to recycle a blended refrigerant because what comes out of the system may not be the same mix that went into the system.
If you would like to read a variety of different views on the subject of alternative refrigerants and retrofits, Click here.
The vehicle manufacturers also say limiting the alternatives to one choice (R-134a) simplifies things, reduces the risk of cross-contamination and eliminates the need for multiple recovery machines. EPA rules require a separate dedicated recovery only or recovery/recycling machine for each type of refrigerant serviced.

ALTERNATIVE REFRIGERANT BLENDS

Alternative refrigerants that have been found acceptable for automotive applications or are currently being reviewed by the EPA include the following blends:
  • Free Zone (RB-276). Supplied by Refrigerant Gases, this blend contains 79% R-134a, 19% HCFC-142b and 2% lubricant.
  • Freeze 12. Supplied by Technical Chemical, this blend contains 80% R-134a and 20% HCFC-142b.
  • FRIGC (FR-12). Made by Intermagnetics General and marketed by Pennzoil, this blend contains 59% R-134a, 39% HCFC-124 and 2% butane.
  • GHG-X4 (Autofrost & McCool Chill-It). This blend is supplied by Peoples Welding Supply and contains 51% R-22, 28.5% HCFC-124, 16.5% HCFC-142b and 4% isobutane (R-600a).
  • GHG-HP. Also supplied by Peoples Welding Supply, this blend contains 65% R-22, 31% HCFC-142b and 4% isobutane (R-600a).
  • Hot Shot\Kar Kool. Supplied by ICOR, this blend contains 50% R-22, 39% HCFC-124, 9.5% HCFC-142b and 1.5% isobutane (R-600a).
The suppliers of the alternative blends say their products typically cool better than straight R-134a in systems designed for R-12, and do not require changing the compressor oil or desiccant in some cases. Changing the desiccant to XH-7 is usually recommended if an R-12 system is converted to R-134a. The desiccant should also be replaced if a blend contains R-22 because R-22 is not compatible with XH-5 or XH-7 desiccant. The recommended desiccant in this case would be XH-9.
The suppliers of the alternative blends also insist the fractionation problem is exaggerated and do not foresee any major problems with recovering and recycling their products (recycling blends is currently illegal, but the EPA is reviewing its feasibility).
One supplier of these products say they sold several million pounds of their alternative refrigerant, so the public is accepting it.


MACS ALTERNATIVE REFRIGERANT FIELD STUDY

A field study of various refrigerants conducted by the Mobile Air Conditioning Society (MACS) in 2003 compared the cooling performance of R-12, R-134a and three blended refrigerants (Freeze 12, FRIGC and McCool Chill-It). The study found that all the alternative refrigerants (including R-134a) did not cool as well as R-12 in the vehicles tested (a 1990 Pontiac Grand Am and a 1987 Honda Accord). But the study did find that the blends outperformed R-134a in the Honda (but not the Pontiac). The increase in A/C outlet temperature with the different refrigerants ranged from less than a degree to almost 11 degrees.

ILLEGAL REFRIGERANTS

Another class of alternative refrigerants has also appeared on the scene: illegal refrigerants. Some products that have been introduced (OZ-12, HC-12a, R-176 and R-405a) do not meet the EPA criteria for environmental acceptability or safety. Flammable refrigerants such as OZ-12 and HC-12a that contain large quantities of hydrocarbons (propane, butane, isobutane, etc.) have been declared illegal for use in mobile A/C applications, but are still turning up in vehicle systems anyway because of their cheap price.
WARNING: Flammable refrigerants pose a significant danger to the occupants inside a vehicle should a leak occur. A spark from a cigarette or a switch can ignite the leaking refrigerant causing an explosion and turning the car into a bomb. It only takes about four ounces of a flammable hydrocarbon refrigerant such as propane or butane to create an explosive mixture inside a typical automobile passenger compartment.
Frontal collisions can also release the refrigerant if the condenser is damaged, which could result in a severe underhood fire causing extensive damage to the vehicle.
There is also a risk to service technicians and do-it-yourselfers who might encounter leaks while servicing a vehicle or operating recovery/recycling equipment.
Merely topping off an A/C system with a flammable hydrocarbon can make the entire charge of refrigerant flammable if the amount added exceeds a certain percentage: 10% in the case of an R-12 system and only 5% with R-134a! That is only three or four ounces of hydrocarbon depending on the overall capacity of the system.
Flammable refrigerants are used in some stationary applications as well as truck trailer refrigeration units because there is less risk of leakage or fire. Also, the amount of refrigerant is typically much less, only five or six ounces total instead of several pounds.

BOOTLEG REFRIGERANTS

Less dangerous but equally illegal is bootleg R-12 that is being smuggled into the U.S. from offshore. Though most of the industrialized nations have stopped manufacturing R-12 (production ended in the U.S. December 31, 1995), R-12 is still being made in some Third World countries including Mexico. Some of this product is finding its way past customs in mislabeled containers or concealed in various ways. The EPA warns that much of the refrigerant it has confiscated thus far is of poor quality, contaminated by air, moisture, R-22 and other substances. The EPA has worked with customs authorities and the FBI to make a number of arrests. Fines for violating the clean air rules can run up to $25,000 per instance.
Counterfeiting branded product is another scam that is being perpetrated to turn a fast buck in today's market. Cylinders of counterfeit Allied Signal Genetron R-12 have reportedly been turning up in various parts of the country. The cylinders do not contain R-12 but some "unknown" refrigerant. Allied Signal says the counterfeit boxes do not have cut-outs where lot numbers strapped on cylinders would appear and there are no bar codes or white painted stripes on the sides. The number "Q 1167" may also appear on the bottom of the packaging. The cylinders themselves may be marked with a pressure-sensitive decal whereas the genuine product has markings printed on the cylinder itself.

CONTAMINATED REFRIGERANT

The high price of R-12 has also lead to an increase in incidences of virgin R-12 being adulterated with other less expensive refrigerants. Most technicians assume a tank of virgin refrigerant is pure, but some are finding that is not the case. Some suppliers say they now test every single tank of refrigerant to make sure it contains the proper refrigerant and that the quality of the refrigerant meets specifications.
The primary threat of contamination, though, is that of accidentally cross-contaminating refrigerants when vehicles are professionally serviced. Because the law requires all refrigerants to be recovered, there is a potential risk of contaminating when recovery and recycling equipment is connected to a vehicle. The problem is compounded, many say, by the proliferation of alternative and illegal refrigerants.
The dangers of cross-contamination are the effects it can have on cooling performance and component reliability. R-12 and R-134a are not compatible refrigerants because R-134a will not mix with and circulate mineral-based compressor oil (which may lead to compressor failure). Nor is R-134a compatible with the moisture-absorbing desiccant XH-5, which is used in many R-12 systems.
Intermixing refrigerants can also raise compressor head pressures dangerously. Adding R-22 (which is used in many stationary A/C systems but is not designed for use in mobile A/C applications) to an R-12 or R-134a system may raise head pressures to the point where it causes the compressor to fail. Straight R-22 can cause extremely high discharge pressure readings (up to 400 or 500 psi!) when underhood temperatures are high. R-22 is also not compatible with XH-5 and XH-7 desiccants used in most mobile A/C systems.
R-134a also requires its own special type of oil: either a polyakylene (PAG) oil or a polyol ester (POE) oil. The OEMS mostly specify a variety of different PAG oils because some compressors require a heavier or lighter viscosity oil for proper lubrication (though General Motors does specify only a single grade of PAG oil for most service applications). The aftermarket generally favors POE oil because POE is compatible with both R-12 and R-134a and unlike PAG oil it will mix with mineral oil. Mineral oil, as a rule, should still be used in older R-12 systems.

SHOULD YOU USE AN ALTERNATIVE REFRIGERANT?

The use of alternative refrigerants in older R-12 vehicles will continue because in some cases there is no other option other than converting to R-134a. Vehicle manufacturers discourage using alternative refrigerants and recommend R-134a for retrofitting older R-12 systems.
DO NOT use any alternative refrigerant in a vehicle with a R-134a A/C system (most 1995 and newer vars and trucks). This is illegal and may cause cooling problems and/or compressor failure.
DO NOT use any alternative refrigerant in newer vehicles that have a R-1234yf A/C system. This is also illegal and may cause cooling problems and/or compressor failure.
To minimize the risk of refrigerant cross-contamination, the EPA requires that each type of refrigerant (including alternative blends) have unique service fittings (permanently installed) and proper labeling. The EPA also requires shops to use a separate dedicated recovery/recycling machine for R-12, R-134a and R-1234yf, plus one or more additional recovery only machines for any other refrigerants that might be used. For this reason, many shops choose to avoid blends. But fleets may find blends to be an acceptable alternative if they do not want to convert (or it would cost too much to convert) their vehicles over to R-134a.
To protect recycling equipment against cross-contamination or bad refrigerant, service facilities should use a refrigerant identifier to check every vehicle before it is serviced. An identifier can also help the shop monitor the quality of their recycled refrigerant as well as any virgin refrigerant that might be purchased.
The best advise is this: if you do not know what type of refrigerant is in your vehicle, take it to a shop that has a refrigerant identifier and have it checked. Intermixing different refrigerants can cause cooling problems as well as shorten the life of the A/C compressor.

REFRIGERANT CONTAMINATION ALERT!

As the use of alternative refrigerants grows, so does the risk of cross-contamination. A recent survey by the Florida EPA revealed some startling results. When they tested the refrigerant recovery tanks in about 100 shops, here is what they found:
Thirty-eight percent of the recovery tanks showed some type of contamination! Independent repair garages and service shops had the lowest rate of contamination, but it was still 32% (nearly one out of three). Used car dealers were the worst, with 71% of their recovery tanks (almost three out of four) showing signs of contamination.
Air contamination was the worst problem, being present in 22% of the tanks tested overall. But cross-contamination between R-12 and R-134a was also found in 15% of the tanks. The most cross-contamination (29%) was discovered in used car dealers.

RETROFIT TO r-134A OR NOT?

Use R-12 in all R-12 systems as long as it is available because R-12 provides the best cooling performance in these applications. There is no need to retrofit to R-134a or to use any other refrigerant as long as the system is cooling normally. But if your A/C system requires major repairs such as a new compressor or condenser, the cost to retrofit is justified.
Switching an older R-12 system to R-134a does not require a lot of modifications in most instances. Changing the accumulator or receiver-dryer, removing the old compressor oil and replacing the high pressure switch is generally all that is needed. For more information, consider purchasing the R134A RETROFIT GUIDE on this website.
OEM as well as aftermarket retrofit kits are now available for such conversions. But some vehicles (namely certain Japanese cars that have compressors with Viton compressor seals, or certain older Fords with compressors that can't handle higher head pressures or have small condensers) are not so easy to convert. Changing some of these vehicles over to R-134a requires extensive and expensive modifications. So for these applications an alternative refrigerant may be the best choice if R-12 is unavailable.
Down the road, a number of new alternative refrigerants have been developed that may replace R-134a. For more information about the changes that are coming and why these changes are being required, click here.


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How To Recharge Your Car's Air Conditioner

 Car's Air Conditioner Recharge Procedure


a/c recharging


LOW REFRIGERANT

If your air conditioner is not cooling well because the system is low on refrigerant, recharging the system with refrigerant should restore normal operation. This can usually be done with a few cans of refrigerant and a simple service hose connection.

A/C RECHARGING PRECAUTIONS

First, wear safety glasses to protect your eyes. Also avoid skin contact with refrigerant. The chilling effect of spilled refrigerant can cause instant frostbite on bare skin or eyes!

WHAT TYPE OF REFRIGERANT?

Next, you need to figure out what type of refrigerant your vehicle requires:
On 1995 and newer passenger cars and light trucks, the correct refrigerant is R134a. DO NOT use any other type of refrigerant.

On most 1994 and older passenger cars and light trucks, the original refrigerant was R12. R12 is no longer available to do-it-yourselfers and is very expensive. When older vehicles with R12 A/C systems need refrigerant, they can be refilled with recycled R12 from other older cars (this requires taking your car to a repair shop for professional service), or with some alternative refrigerant other than R12, or with R134a (which requires certain modifications).
CAUTION: Mixing different types of refrigerants is NOT recommended. Use the same type of refrigerant that is already in the system unless you are converting an older R12 system to R134a or another refrigerant.
WARNING: Flammable refrigerants are illegal. DO NOT use any type of flammable refrigerant (propane, butane or flammable hydrocarbons).
For more information, see Flammable Refrigerants
Click here for more information about retrofitting older vehicles with R12 A/C systems to R134a.

LOCATE THE SERVICE FITTINGS

Next, you need to locate the service fittings on the A/C system. There are two: a LOW side fitting and a HIGH side fitting. The LOW side fitting is usually located on the suction hose or line that goes from the accumulator to the compressor. The HIGH side fitting is located on the line that goes from the compressor to the condenser.
ac low and high side service fittings





On older R12 systems, the LOW and HIGH pressure service fittings are screw-type schrader valves. On newer R134a systems, the LOW and HIGH side service fittings are quick-connect style fittings. The LOW pressure fitting is SMALLER than the HIGH pressure fitting.

air conditioning refrigerant can hookup for recharging

AIR CONDITIONING RECHARGE PROCEDURE

1. Connect the recharge service hose and valve to a can of refrigerant.

2. Turn the valve on the service hose to puncture the top of the can.

3. SLOWLY turn the valve back out to release a small amount of refrigerant into the hose. This will blow air out of the hose (which you do not want in your A/C system). 

4. Close the valve so no more refrigerant escapes, then quickly connect the other end of the service hose to the LOW pressure service fitting on the A/C system.
CAUTION: DO NOT connect a can of refrigerant to the HIGH side service fitting. The operating pressure inside the A/C system when it is running may exceed the burst strength of the can, causing the can to explode! This should be impossible to do because the service hose for recharging the A/C system will only fit the smaller LOW pressure service fitting. Even so, you should be aware of the danger.

5. Hold the can UPRIGHT so no refrigerant liquid enters the service hose. You only want VAPOR to be pulled into the A/C system (the compressor may be damaged if it sucks in a big dose of liquid!).

6. OPTIONAL BUT HIGHLY RECOMMENDED: You should use a gauge to monitor the recharging process. Though not absolutely necessary, a gauge will help you recharge your A/C system more accurately, and reduce the chance of undercharging or overcharging (either of which will reduce cooling performance).

A high pressure A/C gauge can be connected to the HIGH pressure service fitting, or a low pressure A/C gauge to the LOW pressure service fitting, or gauges can be attached to both fittings (that is what professional technicians do).

NOTE: Some DIY recharging kits include a low pressure gauge on the service hose or on a trigger-grip style can dispenser.

 .. 

7. Start the engine and turn the A/C on MAX/HIGH.

8. NOTE: The compressor may not engage if the system is too low on refrigerant. The low pressure cutout switch will prevent the compressor from running if the system is too low on refrigerant (this is done to protect the compressor from damage due to a lack of proper lubrication). The compressor must be running to suck refrigerant through the service hose into the system. So if it is not engaging when you turn the A/C on, you may have to supply battery voltage directly to the compressor clutch using a fused jumper wire. Look for a single wire connector near the front of the compressor, unplug it and hook up a jumper wire to the battery POSITIVE terminal. This should cause the clutch to engage and the compressor to run.

9. OPEN the valve on the service hose so refrigerant vapor will flow from the can into the A/C system. It may take up to 10 minutes or more per can to suck all of the refrigerant out of the can into the A/C system. Feel the air coming out of the ducts inside the vehicle. It should be getting colder.

10. If you are using a high or low pressure gauge (or both) to monitor recharging, look at the gauge(s). 

LOW pressure gauge: When the reading is between 25 and 40 psi with the A/C running, STOP. The system is fully charged and should be cooling normally. DO NOT add any more refrigerant. If the gauge is over 50 psi, you have overcharged the system with too much refrigerant.

High pressure gauge: When the reading gets up around 200 to 225 psi (R12), or225 to 250 psi (R134a),STOP. The system is fully charged and should be cooling normally. DO NOT add any more refrigerant.

NOTE: The high and low pressure readings will vary depending on the system and ambient temperatures (higher temperatures cause higher system pressure readings).

Refer to the vehicle manufacturer specifications for normal system operating pressures, and the total refrigerant capacity of the system. Most newer passenger car A/C systems do not hold much refrigerant (only 14 to 28 oz.), so you don't want to add too much if the system is low. One can of R134a typically holds 12 oz. of refrigerant.

11. If the system needs more refrigerant after adding one can, you can add a second can. CLOSE the valve on the service hose, then disconnect the hose from the empty can, screw a new can onto the service hose valve, turn the valve to puncture the new can, then turn the valve all the way back out again so refrigerant can flow through the hose into the A/C system.

When you have finished, turn the engine off. CLOSE the valve on the can of refrigerant before disconnecting the service hose from the LOW pressure fitting (in case there is any refrigerant left in the can). Don't vent any left over refrigerant from the can. Leave the service hose attached to the can with the valve closed so you can save the refrigerant for a future recharge.

Remember to replace the plastic caps over the service fittings, and remove the jumper wire from the compressor if you had to jump it to make it run.
IF THE A/C SYSTEM STOPS BLOWING COLD AIR AFTER A FEW DAYS, WEEKS OR MONTHS
If your A/C stops blowing cold air several days, weeks or months after you recharged it, it means the system has a leak and the refrigerant is escaping. You should add some leak detection dye to the system to find the leak. The leak should then be repaired before the system is recharged again, otherwise you are just wasting your time recharging the system over and over again.


Air Conditioning Related Articles:

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Troubleshoot Air Conditioning

Air Conditioning Repairs And Services


A/C COOLING PROBLEM?
The most likely cause of an automotive air conditioner cooling problem is no refrigerant in the system. If the refrigerant has escaped past a leaky compressor or O-ring seal, leaked out of a pinhole in the evaporator or condenser, or seeped out through a leaky hose, the leak needs to be identified and repaired before the system is recharged.
On many systems, the compressor will not turn on if the refrigerant is low because the "low pressure safety switch" prevents the compressor clutch from engaging if system pressure is low. This protects the compressor from possible damage caused by a lack of lubrication.
One of the first things you should check, therefore, is compressor engagement. If the compressors magnetic clutch is not engaging when the A/C is turned on, the problem may be a blown fuse or a wiring problem. If the fuse is blown, replacing it may restore cooling temporarily. But the underlying reason for the fuse blowing in the first place needs to be identified and corrected to prevent the same thing from happening again.
If the magnetic clutch is receiving voltage but is not engaging the compressor, the clutch is defective and needs to be replaced. If there is any evidence of leakage around the compressor shaft seal, the seal should also be replaced.
If the clutch works but fails to turn the compressor (the belt may squeal in protest!), the compressor has seized and needs to be replaced.
Compressor failures are usually the result of loss of lubrication, which in turn may be due to low refrigerant in the system, a blockage (such as a plugged orifice tube which prevents refrigerant and oil from circulating to the compressor), loss of lubricant due to leaks or improper service procedures (not adding oil to the system to compensate for oil lost through leakage or component replacement), or use of the wrong type of lubricant.
R-12 systems require mineral oil while R-134a systems require various types of PAG oil or POE oil. Using mineral oil in a newer R-134a system can cause serious lubrication problems as can using the wrong grade (viscosity) of PAG oil. Always follow the vehicle or lubricant manufacturers compressor oil recommendations.
The next thing you should check when troubleshooting a no cooling problem is system pressure. For this, you need a set of A/C service gauges. Attach your service gauges to the high and low service fittings. If both the high and low side pressure gauges read low, the system is low and needs recharging. But before any refrigerant is added, check for leaks to find out where the refrigerant is going.


A/C refrigerant leaks


AIR CONDITIONING PROBLEM: REFRIGERANT LEAKSAll vehicles leak some refrigerant past seals and through microscopic pores in hoses. The older the vehicle, the higher the rate of seepage. Newer vehicles have better seals and barrier style hoses so typically leak less than a few tenths of an ounce of refrigerant a year. But system capacities also tend to be smaller on newer vehicles, so any loss of refrigerant will have more of an adverse effect on cooling performance.
Various methods can be used to check for leaks. The telltale oil stains and wet spots that indicate leaks on older R-12 systems are less apparent on the newer R-134a systems because PAG lubricants are not as "oily" as mineral oil. This makes it harder to see leaks.
Leaks can be found by adding special dye to the system (available in pressurized cans premixed with refrigerant), an electronic leak detector, or plain old soapy water (spray on hose connections and watch for bubbles -- requires adding some refrigerant to system first and turning the A/C on). Once you've found a leak, repairs should be made prior to fully recharging the system. Most leak repairs involve replacing O-rings, seals or hoses. But if the evaporator or condenser are leaking, repairs can be expensive.


A/C diagnosis chart


POOR COOLING PERFORMANCE
Diagnosing an A/C cooling problem is best done by connecting a gauge set to the high and low pressure service fitting on the system. Though poor cooling is often due to a low charge of refrigerant, it can also be caused by many other factors (see chart above).
How to tell if your A/C system needs refrigerant: look at the LOW pressure gauge reading when the engine is OFF. On an 80 degree day, the LOW gauge should read about 56 psi or higher if the A/C system contains an adequate charge of refrigerant. On a 90 degree day, the LOW side reading should be about 70 psi or higher. If the LOW gauge reading is less than this, the A/C system probably needs some additional refrigerant.
Refer to the vehicle manufacturer specifications for normal system operating pressures, and the total refrigerant capacity of the system. Most newer passenger car A/C systems do not hold much refrigerant (14 to 28 oz.), so you don't want to add too much if the system is low.
AIR CONDITIONER PROBLEM: INTERMITTENT COOLING
Evacuating the system with a vacuum pump will purge it of unwanted air and moisture. Evacuation should be done with a vacuum pump that is capable of achieving and holding a high vacuum (29 inches) for at least 30 to 45 minutes.

An A/C system that blows cold air for awhile then warm air is probably freezing up. This can be caused by air and moisture in the system that allows ice to form and block the orifice tube.
For best performance, an A/C system should contain less than 2% air by weight. For every 1% increase in the amount of air that displaces refrigerant in the system, there will be a corresponding drop of about one degree in cooling performance. More than 6% air can cause a very noticeable drop in cooling performance, and possibly cause evaporator freeze-up.
Air can get inside a system through leaks, by not evacuating the system prior to recharging it, and/or by recharging the system with refrigerant that is contaminated with air. Recovery equipment can suck air into the recycling tank if an A/C system contains air or if the system has a leak. For this reason, the refrigerant recovery tank on recycling equipment must be checked and purged daily. On some equipment, this is done automatically. But on equipment that lacks an automatic purge cycle, tank pressure and temperature has to be measured and compared to a static pressure reference chart.
Some refrigerant identifier equipment can detect air in the system as well as other contaminants. An identifier should be used to check the refrigerant before the system is serviced to prevent cross-contamination of recovery and recycling equipment.
Possible causes of intermittent cooling in a manual A/C system that might be caused by an electrical problem include:

Faulty low pressure cutout switch. This switch prevents the compressor from running if the refrigerant level is low. If the cutout switch is not reading correctly, it can prevent the compressor from coming on.

Faulty compressor clutch. The magnetic clutch on the compressor requires full battery voltage to engage. If the voltage to the clutch is low, or the clutch coils have too much resistance, or the air gap in the clutch is too great, the clutch may not engage to drive the compressor.

Faulty compressor clutch relay. Check to see if the relay is receiving voltage when the A/C is turned on. Also check the relay wiring and ground connections. If bypassing the relay with a jumper wire or routing battery voltage directly to the compressor clutch makes the A/C work, the relay is probably bad.

Faulty A/C control switch. The switch may be worn and not making good contact when it is turned on.
Some possible causes of intermittent cooling (or no cooling) on automatic A/C systems include all of the above, plus:

A problem in the control module or control head (this usually requires using a dealer scan tool to read fault codes and perform self-diagnostics).

A bad temperature sensor (an ambient air temperature sensor, interior air temperature sensor, evaporator temperature sensor, or sunload sensor). Again, a factory scan tool is usually required to perform diagnostics on the system.
AIR CONDITIONING PROBLEM: NOISE
Noise from the compressor usually means the compressor is on its way out. But noise can also be caused by cross-contaminated refrigerant (operating pressure too high), air in the system or the wrong type of compressor lubricant.
Noise can also be caused by hoses or other parts rattling against other components in the engine compartment. Check the routing of the hoses, support brackets, etc., to pinpoint the noise.
TROUBLESHOOTING AIR CONDITIONING ODOR
If a vehicles air conditioner blows out air that smells like the inside of old gym sneaker when the A/C is turned on, microbes are growing on the evaporator. Mold likes damp, dark places. Bacteria can also thrive under such conditions. Besides smelling bad, it can be unhealthy to breathe (ever hear of Legionnaires Disease?).
To get rid of the unwanted organisms, various chemicals can be sprayed on the evaporator directly or through the blower ducts or air intake. Many replacement evaporators have a special chemical coating that inhibits the growth of mold and bacteria. The drainage tubes that carry condensation away from the evaporator should also be inspected and cleaned.
A/C FLUSHING
If the compressor has failed, or the system is full of sludge or contamination, the condenser, evaporator and hoses should all be flushed with an approved flushing chemical (such as Dura 141b) to clean the A/C system. Flushing can help prevent repeat compressor failures and system blockages by dislodging and cleaning out sludge and debris. Replacing badly contaminated parts such as the condenser, accumulator or receiver-drier and orifice tube or expansion valve is another way to get rid of these contaminants, but flushing is usually a more practical and economical choice. Regardless of which approach you use, the orifice tube or expansion valve should always be replaced when contamination is found.
NOTE: Some types of compressors can be very difficult to flush completely. These include "parallel" flow condensers and those with extremely small passegeways. If contaminated, these types of condensers must be replaced to reduce the risk of a repeat compressor failure. Installing an in-line filter is also recommended for added insurance,
When a compressor fails, a lot of metallic debris is often thrown into the system. Most of this debris collects in the condenser where it can cause blockages that reduce cooling performance. If the debris is carried through the condenser and enters the liquid line, it can plug the orifice tube or expansion valve. This can block the flow of refrigerant and lubricating oil causing a loss of cooling and possible compressor damage. Debris can also migrate backwards from the compressor through the suction hose causing blockages in the accumulator or receiver-drier.
Another source of trouble can be debris from old hoses that are deteriorating internally. Tiny flakes of rubber can be carried along to the orifice tube or expansion valve and cause a blockage.
Sludge is usually the result of moisture-contamination. The blackish goo that results can damage the compressor and plug the orifice tube or expansion valve. The moisture-absorbing "desiccant" in the accumulator or receiver-drier is supposed to prevent this from happening. But the desiccant can only hold so much moisture. Once saturated, sludge begins to form. So you should also replace the accumulator or receiver-drier if the system is contaminated, has leaks or must be opened up for repairs.
Another reason for flushing is to remove residual lubricating oil from the system. This should be done when retrofitting an R-12 system to R-134a. It should also be done if the lubricating oil is contaminated or the system contains the wrong type of oil for the application. Flushing out the old oil can prevent oil overcharging, reduced cooling performance and/or lubrication incompatibility problems.
For added insurance after flushing, you can install a high side filter to protect the orifice tube or expansion valve from any residual debris that might still be in the system, and/or a second filter in the suction hose to protect the compressor.
R134A RETROFIT
As long as R-12 is available, there is no real reason to convert older vehicles to R-134a. That is because R-12 systems cool best when charged with R-12 refrigerant. But converting to R-134a does make sense if your A/C system requires major A/C repairs (such as a new compressor, condenser or evaporator). The extra cost involved to make the changeover to R-134a does not add that much to the total repair bill.
A basic retrofit procedure can be done one of two ways. The "Type 1" retrofit follows the OEM recommended procedure and generally involves removing all the old mineral oil from the system, replacing the accumulator or receiver-drier with one that contains a desiccant (X-7) which is compatible with R-134a, replacing O-rings (if required), installing or replacing a high pressure cutout switch and/or orifice tube (if required), then adding the specified PAG oil and recharging the system with R-134a. Federal law also requires the installation of R-134a fittings on the high and low service ports to reduce the chance of refrigerant cross-contamination the next time the vehicle is serviced, and labels that identify the system has been converted to R-134a. For more information, see the R134A RETROFIT GUIDE program featured on this website.
 Click on image for more info
A "Type 2" procedure is more of a "quick and cheap" approach to retrofit. On many 1989 through 1993 vintage vehicles, the R-12 A/C systems can be converted to R-134a by simply recovering any of the R-12 that is left in the system (NOTE: it is illegal to vent refrigerant into the atmosphere!), adding POE oil (which is compatible with both types of refrigerant), and then recharging with R-134a.
NOTE: Type 2 conversions cannot always be done on some vehicles because their compressors may not be compatible with R-134a (any compressor with Viton seals has to be replaced). This includes original equipment compressors such as Tecumseh HR980, some Keihin compressors and some Panasonic rotary valve style compressors in older Nissan vehicles.

Durability is another concern. Because R-134a raises compressor discharge pressures and increases the compressors work load, some lightweight compressors may not be rugged enough to tolerate R-134a over the long haul. This applies to the Harrison DA6 and Ford FX-15 compressors. The Harrison DA6 can be replaced with a HD-6, HR-6 or HR-6HE compressor. The Ford FX-15 compressor can be replaced with a FS-10 compressor.


More Air Conditioning Articles:

Air Conditioning Inspection Checklist

Troubleshoot Automatic Climate Control System

A/C Cooling Problem: Blows Warm Air Only No Cool Air

How To Recharge Your Car's Air Conditioner

A/C Service Equipment: What's Required To Service Today's Vehicles

Air Conditioning Service Best Practices (Procedures a repair shop should follow when servicing your A/C system)

MACS Recommended A/C Service Procedures (pdf file) 

MACS 2004 A/C Technical Update

A/C Compressor Failures - May 2003

PAG oil recommendations

A/C Condenser Flushing

A/C Update: MACS Report - Jan 2001

OEM Service Note from MACS Convention - Jan 2000

Update on R134a Retrofit - Feb 2000

Alternative Refrigerants

HFO-1234yf Refrigerant

California proposes ban on R134a sales to motorists
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Auto Air Conditioner Blowing Warm Air, Not Cooling

Auto Air Conditioner Blowing Warm Air, Not Cooling


Is you car's air conditioner blowing warm air only and no cool air? Your A/C cooling problem could be caused by any of the following:

Your A/C system may have lost its charge of refrigerant. This is probably the most common cause of a no cooling problem. Another possible cause of no cooling may be that your A/C compressor is not be engaging when you turn on the A/C. This can be caused by an electrical fault in the A/C compressor circuit or the magnetic clutch that drives the compressor. Another cause could be an internal obstruction inside the refrigerant circuit that is preventing refrigerant from circulating inside the A/C system. Another possibility might be a blend air door inside the HVAC unit that is stuck in the HEAT position and is preventing air from flowing through the A/C evaporator.

car a/c ducts


Compressor Checks

 Start with the compressor. Does it engage when you turn on the A/C?
If so, the compressor is working and the A/C system probably contains enough refrigerant to make cold air, so the problem is inside the HVAC unit. Replace the motor that controls the blend air door (this is a difficult job and best left to a professional since it involves tearing apart the HVAC unit -- about an 8 to 10 hour job!).
If the compressor does not engage when you turn on the A/C, see if it will run by jumping the compressor clutch wire directly to the battery (use a fused jumper wire). If the compressor works when you jump it, and the A/C blows cold air, the system contains refrigerant and the fault is likely a bad A/C compressor clutch relay or a bad clutch cycling switch or pressure switch.
If the compressor does not engage when you jump it, the problem is a bad compressor clutch.
If the clutch engages but the compressor does not turn (the belt will start to slip and squeal), the compressor is locked up and you need a new compressor.
If the compressor clutch engages and turns the compressor, but the A/C still does not blow cold air, the system is probably low on refrigerant and needs to be recharged.

Refrigerant Checks

 Connect an A/C pressure gauge to the HIGH SIDE service port (located in the high pressure hose that runs between the compressor and the condenser in the front of the engine compartment). The gauge will tell you if there is any pressure in the system. Simply depressing the service fitting valve with a small screwdriver to see if any refrigerant squirts out is NOT an accurate check because it tell you how much pressure is in the system. It may still have some pressure but not enough to trip the low pressure safety switch so the compressor will engage.
If your A/C system is low or out of refrigerant, check for leaks, then have the A/C system vacuum purged to remove air. After the air is out, it can be recharged with the specified amount of refrigerant. It is important to get any air out as this will reduce cooling efficiency and may make the compressor noisy.

A/C System Functional Checks

 If the refrigeration circuit seems to be working (refrigerant in the system, compressor running and building pressure), but there is still no cooling, the problem might be an obstruction in the orifice tube (located in the high pressure hose between the condenser in the front of the radiator, and the evaporator located in the passenger compartment). A blockage here will prevent the refrigerant from entering the evaporator or recirculating through the refrigeration circuit.
If the orifice tube is plugged, the high side pressure reading will be lower than normal, and the low side reading will also be lower than normal because no refrigerant is circulating through the system.
 If the refrigeration circuit seems to be functioning normally (compressor running, frost or condensation on the high pressure line from the condenser to the evaporator), but no cool air is blowing out of the ducts inside the car (and the blower is working), the fault is likely a BLEND AIR door that is stuck in the HEAT position, or possibly a badly clogged cabin air filter that is restricting airflow. Another possibility would be a fault in the automatic climate control system such as a ad interior temperature sensor or control module.
My advice to you if you know nothing about A/C service is to find a repair shop that specializes in A/C repairs and let them diagnose and repair your air conditioning cooling problem. Today's A/C systems with automatic climate control are very complex and require special tools and know-how to diagnose and repair.


Air conditioning diagnostic chart


This air conditioning diagnostic chart shows typical Low and High side gauge readings, and duct temperatures for common A/C cooling problems.

A/C Gauge Readings

To determine the HIGH SIDE and LOW SIDE pressures inside your vehicle's air conditioning system, you need an A/C Gauge Set. The Gauge Set must be connected to the A/C service ports on vehicle to read the pressures while the system is running.
With the engine OFF, connect the A/C Gauge Set High Pressure Hose (the one with the larger coupler fitting) to the High Side service port (usually located in the compressor output line that goes from the compressor to the condenser). Connect the Low Pressure Hose (the one with the smaller coupling) to the Low Side Service port (usually located on the accumulator, or on the suction hose that goes from the evaporator to the compressor).
Start the engine, turn on the A/C to MAX, and rev the engine to 2000 RPM. Hold the engine speed and note the High and Low side pressure gauge readings.
NOTE: High and Low side pressure readings will vary with ambient temperature and humidity. The higher the temperature and/or humidity, the higher the gauge readings.
With late model R134a systems, good high pressure readings should range from 150 to 220 PSI at 80 degrees F, 170 to 250 PSI at 90 degrees F, and 195 to 280 PSI at 100 degrees F.
A High side pressure reading of less than 150 PSI indicates a low charge or a compressor problem. A high pressure reading over 300 PSI would indicate an overcharge condition (too much refrigerant in system) or a restriction in the high side.
Good low pressure readings with R134a should usually be in the 30 to 35 PSI range. If higher, there may be a low side restriction. If the reading is lower, the system may be low on refrigerant.
With older R12 A/C systems (1994 model year vehicles an older that have NOT been retrofitted to R134a), the HIGH side pressure readings will typically be 150 to 185 PSI at 80 degrees F, 175 to 205 PSI at 90 degrees F, and 200 to 250 PSI at 100 degrees F. Normal LOW side readings with R12 should be around 20 to 30 PSI for an expansion valve system, or 15 to 40 PSI for an orifice tube system.


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How to Check Your Car's Air Conditioning System

Car's Air Conditioning System Inspection & Checking


automotive air conditioning service

You should check your car's A/C system BEFORE hot weather arrives to make sure it is working properly and blowing cold air. The following tips on how to check your car's air conditioning system has been provided by the Mobile Air Conditioning Society (MACS):

Note: Always be extremely careful any time you are under the hood while the engine is running. Stay away from all rotating components with your hands, clothing, and hair, and always wear eye protection around a running engine.

 1. With the engine running, does the compressor clutch engage when the A/C is switched on? If it does not, this usually indicates a low (or empty) refrigerant condition, or an electrical problem. Also, listen for rapid clicking or cycling noises at the compressor when the A/C is switched on. If this is happening, it could also indicate low refrigerant or some other problems. Have it checked by your service technician. (Note: Some A/C systems prevent compressor clutch engagement in low temperatures, typically at or below 40° F.)


 2. Is the A/C system blowing cold air? Luke warm air or air that is barely cooled at all could indicate a low refrigerant charge in the A/C system. Pressure gauges can be used to check the refrigerant charge. If low, add refrigerant to bring the system up to full charge. See How To Recharge Your Car's Air Conditioner for more information on how to add refrigerant.


 3. With the engine running and the A/C switched off, listen for knocking or rumbling sounds in the vicinity of the compressor. These could indicate a failing compressor clutch, and/or loose mounting hardware.


 4. Are A/C component mounting bolts in place and tightly secured? Nothing loose or rattling around?


 5. Are caps installed on the A/C system service ports? This keeps out dirt, and also provides a seal for refrigerant.


 6. Check all belts for cracks, wear, and glazing. Have them replaced at the first sign of any of these conditions. Also, check for belts that vibrate while the engine is running and the A/C is on. This may indicate a belt that needs to be tightened, or a defective automatic belt tensioner.


 7. Examine all A/C and cooling system hoses for cuts, abrasion, weak spots, and signs of leakage. Leakage from A/C system hoses is often indicated by an accumulation of dirt and oil, particularly at connections and fittings.


 8. Make sure the condenser (in front of the radiator) is free of any obstructions, such as leaves or insects. This could reduce airflow, resulting in reduced A/C performance. You can rinse the condenser clean with a garden hose.

More Air Conditioning Articles:

MACS Recommended A/C Service Procedures (PDF file)

A/C Cooling Problem: Blows Warm Air Only No Cool Air

Troubleshooting Air Conditioning Problems

Troubleshoot Automatic Climate Control 

Troubleshooting A/C Cooling Problems with Temperature

Cooling Fan (electric)

Cooling Fan Relay Problems

How To Recharge Your Car's Air Conditioner

Refrigerant Contamination 

Alternative Refrigerants for R-12

New Automotive Refrigerants 
California proposes ban on R134a sales to motorists

Information about Retrofitting older vehicles with R-12 A/C systems to R-134a

A/C Compressor Failures

A/C Condenser Flushing
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