leaderboard 1

Showing posts with label ac recharge. Show all posts
Showing posts with label ac recharge. Show all posts

Saturday 27 June 2015

Air Conditioning Best Service Practices

Air Conditioning Best Service Practices Tried & Tested


automotive air conditioning service


When your car or truck has an air conditioning problem and needs service, what should you do? If your A/C system only needs some refrigerant, you can probably recharge the a/c system yourself. But if you are having cooling problems, leaks or electronic control problems, you should probably seek out a repair facility that specializes in air conditioning service work.
Our advice is to seek out a repair facility that is a member of MACS, the Mobile Air Conditioning Society. MACS is a non-profit trade association for repair shops that do air conditioning service work. MACS promotes training, education, professionalism, and most importantly "Best Practices" for servicing and repairing your vehicle's air conditioning system.
Since 1991, MACS has assisted more than one million technicians to comply with 1990 Clean Air Act requirements for certification in refrigerant recovery and recycling to protect the environment.
Recently, the Climate Protection Partnership division of the U.S. EPA teamed up with MACS to publish and promote six mobile air conditioning best service practices checklists. These checklists are written for professional technicians to help them environmentally safe and technically proper air conditioning service and repairs. The purpose of the checklists is make sure your vehicle is serviced correctly when you take it in for air conditioning service work.
If your shop is NOT following these practices, you should bring it to their attention - or take your vehicle to another shop who does follow the Best Practices recommendations.
Note: The Best Practices guidelines are voluntary recommendations, and are not required by law. Even so, they do reflect current thinking on the best ways to properly service and repair automotive mobile A/C systems. The input for these checklists was provided by highly experienced A/C technicians who are familiar with the right ways and wrong ways of servicing service A/C systems.
The A/C Best Service Practices Guidelines for A/C service include:

A/C Service (general)
Leak Detection
Refrigerant Recovery
System Charging
Field Repair and Assembly of A/C Hoses
A/C Equipment Maintenance.


More Air Conditioning Articles:

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


More Refrigerant Articles:


Refrigerant Resources:



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.


 More Air Conditioning Articles:

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: