Refrigerant types and proper discharging
Refrigerant types and proper discharging
09-16-2006, 10:38 PM
I notice that there are different R134a refrigerants, some that say they get colder than the rest, etc. I was wondering if there were any ones that actually are better than the rest.
Secondly, I was wondering if I did want to replace the refrigerant with a better one, what is the proper way to discharge the refrig. thats already in the system before putting new stuff in? If the 'proper' way is hard to do or w/e, is there a quick and dirty way to do it, that'd get the job done just as well?
09-17-2006, 12:43 AM
R134a is a chemical compound that is only one thing. Marketing types may say that theirs is the best for some reason, but it better be only 134a or they will be liable for any damage done to your car by its use.
09-17-2006, 01:19 AM
Here is an interesting article on alternative refrigerants:
A/C: New Alternative Refrigerants
by Larry Carley
If you have bought any R-12 refrigerant lately, you know it is pretty pricey stuff. Last year, the price peaked at about $20 a pound ($600 for a 30 lb. tank) in some areas of the country. This year some predict the price could shoot as high as $30 to $33 per lb. ($1000 per tank!) if we get a long hot summer. Consequently, people are searching for less expensive alternatives to recharge their A/C systems.
Though some alternative refrigerants are being marketed as "drop-in" replacements for R-12, there is really no such thing. According to the EPA, the concept of a "drop-in" replacement for R-12 is a marketing myth. Such words imply a substitute refrigerant will perform the same as R-12 under all conditions, that it will require no modifications to the A/C system or changes in lubricant, and that it is compatible with R-12 and can be added to a system that still contains R-12. Federal law prohibits the topping off A/C systems with refrigerants that are different from what is in the system—unless all of the old refrigerant is first removed so the system can be converted to a new refrigerant.
The truth is no substitute refrigerant meets all of these requirements. There are, however, a number of alternative refrigerants that have been reviewed by the EPA and have been found to meet the EPA’s SNAP (Significant New Alternatives Policy) criteria for environmental acceptability and usage. The SNAP rules prohibit flammable refrigerants or ones that contain ozone-damaging CFCs.
But just because a refrigerant meets the EPA's usage criteria does not mean it is endorsed or "approved" by the EPA, or that it will perform well as a refrigerant.
There are currently seven alternative refrigerants from which to choose. One is R-134a, which is the only alternative currently approved by all vehicle manufacturers worldwide for new vehicles as well as for converting older R-12 applications. The OEMS say R-134a can perform well in most R-12 systems provided the proper retrofit procedures are followed. The also recommend R-134a because it is a single component refrigerant, unlike most of the alternatives which are blends of two to four ingredients.
The OEMS 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 don’t 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.
The OEMS also say limiting the alternatives to one (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 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).
Are blends establishing a niche in the marketplace? One supplier of these products said they sold over a million pounds of their alternative refrigerant last year alone! Most are predicting increased sales as the price of R-12 continues to rise and stockpiles dwindle.
MACS FIELD STUDY
A field study of various refrigerants conducted by the Mobile Air Conditioning Society (MACS) 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.
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’s 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.
Flammable refrigerants pose a significant danger to a vehicle’s occupants should a leak occur. A spark from a cigarette or a switch can ignite the leaking refrigerant causing an explosion and turning the vehicle’s interior into an inferno. 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’s also a risk to service technicians 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’s 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’s 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.
BOOTLEGGERS & COUNTERFEITERS
Less dangerous but equally illegal is bootleg R-12 that’s being smuggled into the U.S. from offshore. Though most of the industrialized nations have stopped manufacturing R-12 (production ended here 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’s 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.
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’s not the case. Some supplies 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’s 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.
The use of alternative refrigerants such as blends will likely grow because they’re a cheap alternative to R-12. The OEMs don’t like it, but the EPA has said it will let the market decide the fate of alternative blends. Consequently, you need to be aware of what’s potentially out there and be prepared to handle (or not handle) blends.
To minimize the risk of cross-contamination, the EPA requires that each type of refrigerant (including 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 and R-134a, plus one or more additional recovery only machines for any other refrigerants that might be used. For this reason, many shops may choose to avoid blends. But fleets may find blends to be an acceptable alternative if they don’t want to convert (or it would cost too much to convert) their vehicles over to R-134a.
To protect recycling equipment and customer’s vehicles 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.
Most identifiers that are available today can only tell you if the system contains pure R-12, R-134a, hydrocarbons, or R-22 or an "unknown" refrigerant. Each blend has its own characteristic finger print, but because of the fractionation problem getting a precise fix on exactly what’s in a vehicle isn’t as easy as it sounds.
The best advise is this: if you don’t 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 compressor.
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’s 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 OR NOT?
The OEMS say R-12 should be used in all R-12 systems as long as it is available because R-12 provides the best cooling performance in these applications. They say there’s no need to retrofit to R-134a or to use any other refrigerant as long as the system is cooling normally. But if the system requires major repairs such as a new compressor or condenser, the cost to retrofit may be justified.
The OEMS say switching an older R-12 system to R-134a does not require a lot of modifications in many instances. Changing the accumulator or receiver-dryer, removing the old compressor oil and replacing the high pressure switch is generally all that’s needed—a job that can usually be done for less than $200. For more information, consider purchasing the R134A RETROFIT GUIDE (http://www.carleysoftware.com/retrofit.htm)on this website.
OEM as well as aftermarket retrofit kits are now available for such conversions. But some vehicles (namely those with viton compressor seals, compressors that can’t handle higher head pressures or have small condensers) aren’t so easy to convert. Changing some of these vehicles over to R-134a requires extensive and expensive modifications. So for these applications there are no kits or easy answers—other than to switch to a blend refrigerant if R-12 becomes too expensive or is unavailable.
09-17-2006, 07:47 AM
You're guessing, right? :) :)
09-17-2006, 01:14 PM
No, if it's called R134a, then it is only R134a. If it's called Freeze12 or one of the other alternatives listed in the above article, then it's a mixture and I wouldn't use it. They are meant to be used in R12 systems.
09-17-2006, 04:52 PM
4 years ago the compressor died on my 87 Camry wagon so I saw it as a good time to convert to R134. I had it done at an A/C specialist shop. Changed the compressor, drier and pressure valve. They back-flushed the system with a cleaner from several points as well. Total cost was $680. Since then I have had no problems but, as you're saying, it doesn't cool as well as it did with R12. That said, with R12 the system usually cooled too good because I was always setting the blower speed lower or using the econ setting. If I didn't I would freeze even on a warm day. My point? With R12 I was always fiddling with the settings. With R134 for the most part the need to fiddle is gone.
Brian R. - Any chance you could put another "sticky" at the top labeled , "Tips and Tricks". There's always those little helpful things guys learn in general or in a specific procedure while repairing cars that you won't find in a book. Give it some thought.
09-17-2006, 05:50 PM
Thanks for the idea. I have been putting such information into the FAQ thread. Although you have to search for them, the list would still be really long in a special thread and I think you'd end up searching that thread anyway. I am trying to minimize the number of stickies so that there are as many of the user-started threads as possible on the front page.
Also, I hope that anyone needing information will first search the entire forum for relevant keywords. This search would include the FAQ thread (as well as any other Tips and Tricks thread). Since that is the best way to find information before posting, there is no difference between posting stuff like that in a separate thread and posting it all together in the FAQ thread.
If you think there is something I should add to the FAQ thread, just let me know in a PM.
09-18-2006, 09:10 PM
You're guessing, right? :) :)
Sorry if it wasn't obvious, but I was joking.
09-18-2006, 10:06 PM
Doh! I didn't get it...
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