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


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R-12 to R-134A Refrigerant Retrofit

R-12 to R-134A Refrigerant Retrofit



R-134a Retrofit


If you drive an older vehicle (pre-1994), the air conditioning system contains R-12 refrigerant (Freon). As long as the A/C system has no leaks and it cooling normally, there is no need to convert from R-12 to the new "ozone safe" R-134a refrigerant. But if your A/C system has lost it's charge because of a leak, collision damage, or the need to open it to replace a compressor, hose or other component, you may have to convert from R-12 to R-134a when you recharge the system
Why? Because R-12 is no longer produced in the U.S. Supplies of recycled R-12 still exist, and some R-12 is still brought in from offshore suppliers. But it is hard to find and expensive. That's why many people simply recharge their older R-12 air conditioning system with R-134a after repairs have been made.

R-134a Retrofit Conversion Costs

Does it make economic sense to retrofit an older vehicle to R-134a if the A/C system has lost its refrigerant charge or needs major repairs? The older a vehicle gets, the more it depreciates. By the time it is 15 or more years old, it may only be worth a few hundred dollars. Many owners will not put any more money into an older vehicle unless the repairs are absolutely necessary to keep it running. Even then, it may be less expensive to get rid of the vehicle or to junk it than to fix it up. Even so, A/C is something that's hard to do without especially during hot weather. Hot summer temperatures and high humidity can make driving in city traffic unbearable.
A professional retrofit by a repair shop can cost hundreds of dollars, depending on what they do. But on many older vehicles, you can save money and do the job yourself - if you have some know-how and the right equipment.

WHEN R-134A RETROFIT MAKES SENSE

There is NO reason to retrofit a vehicle to R-134a as long as the R-12 system is cooling properly and contains a normal charge of refrigerant. A/C systems designed to use R-12 will cool best when charged with R-12 refrigerant. Even if the system leaks, repairing the leaks and recharging it with R-12 is usually the best repair alternative. Converting to R-134a typically reduces cooling performance somewhat, and may require some additional modifications depending on the vehicle model year.
Where retrofit makes the most economic sense is when an A/C system requires major repairs such as a new compressor, condenser or evaporator.
The average repair bill to retrofit when other A/C repairs are needed, according to the Mobile Air Conditioning Society (MACS), is about $100 over and above any other repairs that may be needed (such as replacing the compressor, condenser or evaporator, etc.). The cost to retrofit usually does not add that much to the total repair bill because converting 1990s vintage vehicles to R-134a in most cases is fairly easy and does not require many (if any) changes. If the vehicle has barrier style hoses and the compressor and seals are compatible with R-134a, the only thing that has to be changed is the compressor lubricant.

TWO WAYS TO DO A R-134A RETROFIT

A retrofit can be done one of two ways. The first is to follow the vehicle manufacturer recommended retrofit procedure. This generally involves removing all the old mineral oil from the system, replacing the accumulator or receiver/dryer with one that contains X-7 desiccant, replacing O-rings (if required), installing or replacing a high pressure cutout switch (which many shops seem to forget), changing the orifice tube or expansion valve (if required), then adding the specified PAG oil and recharging the system with R-134a. On some applications, installing a more efficient condenser may be recommended for improved cooling performance. After the modifications are made, the system is recharged to about 85 to 90% of its original capacity with R-134a.
Federal law also requires the permanent 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. Labels must also be installed to identify the system has been converted to R-134a.
R-134a service fitting adapters
Installing service fitting adapters allows R-134a to be put into a R-12 system.
The other approach to retrofit is the "quick and cheap" one. On many 1989 through 1993 vintage vehicles, R-12 A/C systems can be converted by simply recovering any refrigerant that is still in the system, adding POE oil (which is compatible with both types of refrigerant), and recharging to 85 to 90% capacity with R-134a.
A simple retrofit may therefore cost no more than a few cans of refrigerant and some compressor oil -- provided there's nothing else wrong with the A/C system. But simple low cost retrofits may not give the best cooling performance, and may not even be possible on some vehicles. Any compressor that has Viton seals is not a candidate for retrofit. This includes original equipment compressors such as Tecumseh HR980, some Keihin compressors and some Panasonic rotary valve style compressors on older Japanese cars. On these, the compressor must be replaced.
Compressor durability is also a concern with some vehicles. 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.
Regardless of which retrofit method is used, cooling performance will vary depending on the design of the system. As a rule, expect anywhere from a 3% to 15% decrease in cooling performance when an R-12 system is converted to R-134a. Systems with relatively large or efficient condensers will experience less of a drop in cooling performance with R-134a than those with smaller or less efficient condensers.

ADDITIONAL R-134A RETROFIT TIPS

One way to improve cooling performance when retrofitting an older R-12 system to R-134a is to install a "variable valve" orifice tube in place of the standard fixed orifice tube. These aftermarket variable orifice tubes allow the flow rate through the valve to change for better cooling at idle and low speeds. Such a valve can lower the A/C outlet air temperature by as much as 5 to 8 degrees, which can make quite a difference if the vehicle is crawling along in stop-and-go city traffic.
Adding an extra cooling fan can help boost cooling performance, especially at idle and low speeds. Many older rear-wheel drive cars and trucks do not have a separate electric fan for the A/C condenser. They rely solely on the belt-driven fan for cooling, which may not be adequate in extremely hot weather with R-134a. Installing an auxiliary fan that comes on when the A/C is turned on give provide the extra airflow needed to carry away the heat.
Installing a larger or more efficient condenser can also help compensate for losses in cooling efficiency with R-134a. If the original condenser or evaporator is being replaced because of a leak, damage or defect, make sure the replacement unit has the same or better BTU rating. Some aftermarket replacement condensers and evaporators may not deliver the same cooling performance, and create a problem you did not have before.
When a compressor fails, it can throw metallic debris into the system. Most of the junk ends up in the bottom of the condenser, but some of it can also be blown back into the suction hose. Flushing the condenser, hoses and evaporator with refrigerant or an approved solvent may remove most of the debris, but parallel flow condensers cannot be flushed effectively. Replacement is often recommended if debris is found in the system. Most experts also recommend installing an in-line filter (high side and/or low side) to protect the replacement compressor and orifice tube or expansion valve. There are also filter screens that can be installed in the suction line to prevent any debris from reentering the compressor, too.

ALTERNATIVE REFRIGERANTS

The vehicle manufacturers still do not approve of any alternative refrigerants other than R-134a for retrofit, though a variety of alternative refrigerants currently meet the EPA SNAP (Significant New Alternatives Policy) rules for environmental acceptance. Most of these are blends that are formulated to replace R-12 in older vehicles.
It is important to remember that R-134a or any other alternative refrigerant cannot be mixed with R-12 or used to top off an R-12 system. If an A/C system still contains any R-12 at all, it must be removed using approved recovery equipment (venting is not allowed) before a new refrigerant is added to the system. This is an absolute must to prevent cross-contamination of refrigerants and cooling performance problems.
Mixing different refrigerants can cause big problems. For one, it will increase the system operating pressure. This can result in a loss of cooling performance and may overtax the compressor to the point where it fails. R-134a and mineral oil will not mix. So if somebody recharges an R-12 system with R-134a and does not add a compatible lubricant, the compressor will soon fail.
  • 57% had R-12 and R-134a mixed together (up 10% over last year).
  • 20% had R-22 in R-12 systems.
  • 20% had two or more refrigerants mixed together (down 10% over last year).
  • 30% contained hydrocarbons (propane or other flammable hydrocarbons).
  • 2% had too much air.
The same survey also revealed that only one out of 10 technicians knew about EPA SNAP rules, the Significant New Alternatives Policy regulations that prohibit refrigerant venting, require recovery and recycling, prohibit the intermixing of different refrigerants or the use of flammable refrigerants.
Two out of five technicians also did not know the service fittings on an A/C system MUST be changed if the system is converted from R-12 to R-134a or anything else. And three out of five technicians did not know mixing R-12 and R-134a could cause problems.
For more information about the usage of Alternative Refrigerants, see Alternative Refrigerant Report



Click Here for info about A/C R-134a Retrofit Guide 

 More Air Conditioning Articles:

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

Troubleshooting Air Conditioning Problems

Troubleshoot Automatic Climate Control System

Troubleshooting A/C Cooling Problems with Temperature

How To Recharge Your Car's Air Conditioner

Refrigerant Contamination 

Alternative Refrigerants

New Automotive Refrigerants 

Flammable Refrigerants

California proposes ban on R-134a sales to motorists

MACS Recommended A/C Service Procedures (PDF file - requires Adobe Acrobat Reader to view).

A/C Compressor Failures

A/C Condenser Flushing


To More Technical Info Click Here to See More Carley Automotive Technical Articles
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New Automotive Refrigerants

New Automotive Refrigerants For Your Vehicle


alternative refrigerants


What the future holds for automotive refrigerants is uncertain, but changes are happening and more changes are coming. R-134a refrigerant contineus to be used in many late model vehicles, but many new cars are now being equipped with A/C systems that use R-1234yf refrigerant. Other refrigerants may also be coming as R-134 is gradually phased out in the years ahead.
The Europeans want to phase out R-134a in all new vehicles by 2017. The European rules require any new refrigerants must have a global warming potential of less than 150. The U.S. EPA also wants car makers to switch to a different refrigerant to lower the overall carbon emissions of the vehicle fleet. Carbon credits will be given to auto makers who make the switch to a refrigerant that has a lower Global Warming Potential (GWP).
Though R-134a poses no danger to the ozone layer if it escapes into the atmosphere, it is a "greenhouse gas" with a fairly high global warming potential of 1300 (compared to 1 for carbon dioxide, which is nature's own greenhouse gas). A leak that allows only an ounce or two of R-134a to escape into the atmosphere may not seem like a big deal, but over time it all adds up, especially when you multiply small leaks times the hundreds of millions of vehicles that now share planet Earth with humanity.
According to November 2006 report by the Energy Information Administration, vehicles in the U.S. leaked 50.8 thousand tons of R-134a into the atmosphere, equivalent to to over 66 million tons of greenhouse gases. The emissions are 7% higher than in 2004, and up 273 percent since 1995.
North American auto markers have started to replace R-134a with R-1234yf. Auto makers are also redesigning their A/C systems following goals in mind:

* To use less refrigerant. Some newer A/C systems now use only 12 to 14 oz. of refrigerant, which is much less than the 24 to 60 oz. charges that most older A/C systems use. As time goes on, we will see more and more of these low capacity A/C systems in new vehicles.

* To reduce refrigerant leakage 50% over the life of the vehicle. This requires using improved seal designs, hoses and o-ring connections.

* To improve cooling efficiency 30% with more efficient condensers, compressors and operating strategies (things like variable displacement compressors that run all the time rather than cycle on and off). Mercedes has this now.

* To reduce the cooling requirements inside the passenger compartment 30% by using reflective coatings on glass, heat reflective paint, and venting the interior during hot weather.

Changes are also being made to reduce refrigerant losses when the A/C system on a vehicle is serviced. The latest generation of refrigerant recovery machines do a better job of removing all of the refrigerant from the system. Older machines can leave as much as 20 to 30 percent of the old refrigerant charge in the system. The residual refrigerant can escape into the atmosphere when the A/C system is opened to replace parts. Some of the newest machines can pull up to 95% of the refrigerant out of the system to reduce the amount of R-134a that escapes into the atmosphere.

Auto makers have also been adding leak detection dye to the refrigerant to make it easier for technicians to detect refrigerant leaks. A leak will leave a telltale stain that glows greenish-yellow or greenish-blue when illuminated with an UV light source. Leaks as small as 1/8 oz. of refrigerant per year can be detected this way.
The Europeans auto makers are taking a different approach. They want future A/C systems to be as environmentally benign as possible. That means no chlorine-containing CFCs such as R-12 or R-22 that cause ozone depletion, an no refrigerants that could add to the global warming problem (which includes R-134a). Any new refrigerants must also be nontoxic and safe, though that doesn't necessarily mean nonflammable.
For more information, see Flammable Refrigerants
In an effort to address these issues, the Alliance for Responsible Atmospheric Policy (ARAP) and the U.S. Environmental Protection Agency (EPA) have held a series of annual meetings to discuss and evaluate alternatives to R-134a. The first of these meetings was held in 2003 by the European Commission in Brussels. As a result of that meeting, the European Commission decided to allow carbon dioxide, HFC-152a and other refrigerants as possible replacements for R-134a.

CO2 as an Alternative Refrigerant

When used as a refrigerant, CO2 (called R-744) requires extremely high operating pressures (up to 1,800 psi on the high side, and 350 to 400 psi on the low side), compared to 300 to 400 psi on the high side for R-134a. The reason the pressures are so high is because CO2 does not condense in the refrigeration circuit. It remains in the gaseous state. Consequently, the front heat exchanger is called a "cooler" rather than a condenser.
CO2's main attribute is that it has virtually no impact on global warming or ozone depletion. CO2 is also nontoxic in small doses but concentrations over 5% can be lethal. It is also cheap (about $10 for a 20-lb. cylinder) and nonflammable. Numerous test vehicles with CO2 A/C systems have shown that CO2 does provide cooling performance comparable to R-134a.
SAE has developed service fitting standards for R-744. Leak detection presents a challenge because natural levels of CO2 in the atmosphere may be higher than the amount emitted by a leak from an A/C system. Some type of ultrasound or infrared equipment may be required to find R-744 leaks, but dyes may also work or plain old soap bubbles.

HFC-152a

HFC-152a is almost a straight drop-in substitute for R-134a. The molecule is similar to R-134a except that two hydrogen atoms are substituted for two fluorine atoms. It has similar operating characteristics to R-134a but cools even better. One test in an otherwise unmodified Saturn Ion found that A/C duct outlet temperatures were several degrees C lower with HFC-152a. Fuel efficiency was also up 10% at idle, and 20% at highway speeds. The system typically requires only about two-thirds of the normal charge with HFC-152a and can be used with current desiccants.
An environmental benefit of HFC-152a is that it has a global warming rating of 120, which is 10 times less than R-134a, but still a lot higher than CO2. That is why HFC-152a is currently used in many aerosol products as a propellant. Its main drawback is that it is slightly flammable (Class 2A), but it is not as flammable as propane or most other hydrocarbon-based refrigerants.
The first mobile A/C system to use HFC-152a was unveiled at the Mobile Air Conditioning Society (MACS) Worldwide tradeshow in January 2004; a self-contained unit for off-road construction equipment that featured an oil-driven compressor. Made by Red Dot, the unit was a forerunner of future HFC-152a A/C systems to come.
Red Dot staff explained that the HFC-152a refrigerant used in the self-contained unit improves cooling capacity, decreases fuel use and helps protect the climate. The new technology also satisfies stringent new regulations proposed by the European Commission. Red Dot staff also said that the HFC-152a system uses new technology that will use hydraulic-driven compressors and secondary loop technology to increase reliability, safety and reduce the amount of refrigerant required.

R-1234yf

The refrigerant that may eventually replace R-134a is R-1234yf (also called HFO-1234yf). Developed jointly by Honeywell and DuPont, it is being promoted as a drop-in replacement for R-134a in both new vehicles and older vehicles, should that become necessary in the future. R-1234yf has thermal characteristics that are very similar to R-134a, so no major modifications to the A/C system are necessary. Better yet, R-1234yf has a global warming potential of only 4, compared to 1200 for R-134a, allowing it to meet the European requirements for a GWP of less than 150. Existing refrigerant leak detectors can also detect R-1234yf if it leaks. But R-1234yf is mildly flammable (though less so than HFC-152a), and the industry is still debating its potential safety.
Currently, there are NO plans to make R-1234yf directly available to consumers or do-it-yourselfers (meaning you can't recharge your A/C system yourself if your vehicle has an R-1234yf A/C system). Also, repair shops can only buy the new refrigerant in 10-pound containers, limiting the amount they can keep on hand for service work.
In early 2013, production of the new refrigerant began for a limited number of OEM applications. Production has ramped up as more and more new vehicles with R-1234yf A/C systems are introduced.

Click Here for detailed information about R-1234yf by Honeywell.


Update: November 2008

SAE Says HFO-1234yf is Best Alternative Refrigerant for R-134a

In a recent press release, the Society of Automotive Engineers (SAE) International Cooperative Research Program (CRP) says HFO-1234yf offers "superior environmental performance" for future mobile air conditioning systems that may be redesigned for alternative refrigerants.
The CRP1234-1 and CRP1234-2 programs, launched in 2007, have investigated the safety and performance of the new refrigerant HFO-1234yf. Under the direction of the SAE CRP members (who are international experts in this field from OEMs, Tier 1 and 2 Suppliers and independent test facilities), air conditioning system performance, material compatibility and relative risks of HFO-1234yf were evaluated. Based on these studies, HFO-1234yf was judged to have the lowest risk for use in mobile A/C systems compared to all of the other alternative refrigerants that are currently being evaluated. This is based on the Life Cycle Climate Protection analysis that estimates CO2 Equivalent emissions from automotive A/C usage (as described in SAE J2766).
Click Here to view the SAE CRP1234 report on HFO-1234yf.
The study was conducted in response to European Union regulations that will require all new vehicles made for model year 2011 and later to use a refrigerant with a Global Warming Potential (GWP) below 150. Current automotive A/C systems all use R-134a, which has a GWP of 1,430. HFO-1234yf has a GWP of only four.

Update: October 15, 2009

EPA to Approve HFO-1234yf Refrigerant for Significant New Alternatives Policy (SNAP) program

On Tuesday, October 13, 2009, EPA's Administrator signed a rule proposal that says HFO-1234yf is an acceptable substitute for CFC-12 in motor vehicle air conditioning, subject to use conditions. You can view the proposed rule on EPA's SNAP website athttp://www.epa.gov/ozone/snap/.
The public comment period on this proposed rule is for 60 days, beginning when it is published in the Federal Register early next week. Once the rule is published, you will be able to find information and to send EPA comments on the proposed rule athttp://www.regulations.gov/ , docket EPA-HQ-OAR-2008-0664. The Federal Register version of the proposed rule will be posted by the end of the week of October 19 at http://www.epa.gov/ozone/snap/regulations.html (Rule 16 on HFO-1234yf).

Update: September, 2010

GM to Use R-1234yf Refrigerant in some 2013 Models

GM says that starting in 2013, it will begin using HFO-1234yf refrigerant instead of R134a in the air conditioning systems in some Cadillac models (XTS luxury sedan and ATS sports sedan). This will help GM meet the new greenhouse gas emission rules. The Chevy Volt plug-in hybrid electric, however, will have an R134a air conditioning system (for now).

Update: October 21, 2010

SAE Releases 20 New Standards for R-1234yf Refrigerant

The Society of Automotive Engineers (SAE) has announced 20 new standards covering service procedures, service equipment and vehicle components for the new R-12354yf refrigerant. The standards require auto repair shops to buy all new equipment to service the A/C systems on new vehicles that are equipped with HFO-1234yf. The new equipment requirements are covered in J2911, which includes a provision that the recharging machine must test the A/C system for leaks. If a leak is found, the machine will not recharge the vehicle until the leak is fixed. J2843 covers recovery procedures.
J2845 will require technicians who work on R-1234yf systems to be certified in service and recovery procedures.
There is also a new standard J2842 that prohibits shops from repairing leaky evaporators, or fixing a vehicle with a used evaporator from a salvage vehicle because of possible safety risks. R-1234yf is mildly flammable, so the reason for replacing a leaky evaporator with a new one is to minimize the risk of a repeat leak that might allow the refrigerant to enter the passenger compartment.
Currently, there is no mandate in the U.S. to phase-in R-1234yf by a certain date, so the phase in will be gradual and will likely be spread across many model years as new vehicle models are introduced. This will likely create a LOT of confusion in the years ahead as to which type of refrigerant to use in a particular model year vehicle. R134a or other refrigerants must NOT be intermixed with or substituted for R-12354yf in new vehicles if service is required as damage may result to the A/C system due to different operating pressures.
New vehicles with R-1234yf A/C systems also require a unique type of PAG compressor oil. Compressors for these systems have been redesigned to keep more of the oil in the compressor to improve cooling efficiency. Larger, more efficient condensers are also required because R-1234yf cools about 10 percent less efficiently than R134a.

Update: September 4, 2012

MACS Announces R-1234yf Technician Training Program

The Mobile Air Conditioning Society (MACS) now has a new training program to certify automotive technicians to SAE J2845 under the SAE J2911 program for the upcoming introduction of R-1234yf refrigerants in new vehicles.
SAE International created the J2911 and J2845 standards in response to changes in the refrigerants that will be used in mobile A/C systems. The SAE J2845 standard covers servicing of R-1234yf and R-744 mobile air conditioning (MAC) systems. The training teaches technicians how to identify which refrigerant is in a vehicle, how to handle it safely, and what type of service information, tools and equipment are needed to service the vehicle.

Update: November 2012

Mercedes, BMW and VW say they will NOT use R-1234yf Refrigerant because of Safety Concerns

Citing concerns that the alternative refrigerant R-1234yf can burn in real life conditions inside a vehicle (per lab simulation test results), Mercedes, BMW and Volkswagen said they will NOT switch their vehicles to R-1234yf. At this time, it appears that CO2 may be the best alternative to R-134a, according to the German auto makers.
R-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 R-1234yf is on hold as far as two of the leading German auto makers are concerned.
On a related note, Cadillac has temporarily suspended installing R-1234yf in the ATS sports sedan and XTS luxury sedan. For now, these vehicles will be produced with R-134a pending further investigation into the potential flammability issues with R-1234yf.
Note: See June 26, 2013 update below for more information on this subject.

Update: April 13, 2013

Latest Alternative Refrigerant May be a Blend Called AC-6

To counter the virtual monopoly that Honeywell and DuPont have on the production of R-1234yf refrigerant (which is currently selling to car dealers for around $60 to $70 a pound!), Mexichem has developed a blended refrigerant that could sell for as little as $10 a pound, and would work in any R-134a A/C system. The AC-6 blend contains 85 percent R-1234ze, 9 percent R-134a and 6 percent CO2. The Global Warming Potential (GWP) of the new blend is 6.0, which is well under the GPW requirement of 150.
For AC-6 to be approved, the auto makers would have to do extensive testing, and the EPA would have to add it to its approved alternative refrigerant list.
The main drawback of a blended refrigerant is that some of the ingredients in the mix tend to leak out of an A/C system faster than others, effectively changing the blend over time and its thermal characteristics. Currently, there is no aftermarket A/C service equipment that can reconstitute a blended refrigerant. If an A/C system charged with AC-6 required service, the old refrigerant would have to be recovered from the system and replaced with new refrigerant rather than recycled.

Update: June 26, 2013

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

After extensive testing and review, SAE International has concluded that Honeywell's new R-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.

Update: April 2014

R-1234yf A/C Systems Now in Production

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.



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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.


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