Automotive air conditioning and R12 updates (R134a and more)

The Weisners wrote:

If there was ever a time to get a second or third opinion, it's the A/C business...I'm not saying everybody is dishonest, but there are unfortunately many who are. I have had many people bring cars to me who have been told that they need condensers, evaporators, compressors, etc. replaced at considerable cost when all they needed is simply replacing some o rings . Most times you can spot leakage of refrigerant by looking for a oily spots around connections or on condenser coil area. So do a little checking yourself. You will definitely have to have a professional do the work but be alert and protect yourself.
I strongly suggest if you have to have a major repair or replacement done that you consider changing over to a R 134A system. It will save you money in the long run, since the price of R 12 refrigerant is already sky high and it will get much higher as time goes by. I also would suggest to spend the extra money for a new component(when it comes to replacing condenser or evaporator). I've never had much luck with used ones.

There are two basic types of air conditioning system in the United States: R12 based, or "the old kind" which disappeared in the mid-1990s, and R134a-based, or "the new kind" which brings all sorts of problems with it, mainly leak-based. While good cold air conditioning was a given in the 1970s, with systems lasting well over ten years with no need for refills, air conditioning problems today seems to be a major reason for junking cars, and repairs are much more expensive. There was a good reason for giving up R12 - that is, the depletion of the ozone layer, which could no longer be written off as a product of the imagination of a small group of left-wing liberal loonies but was clearly hard reality with dire effects if it was allowed to continue at the same pace. R134a was adopted, and many say it was adopted solely because DuPont had a patent on it; Australia, incidentally, uses a cheaper and more efficient hydrocarbon-based system.

Here is some infomration from the EEK! list and Allpar's main forums.

Installing a new system

Bob Lincoln wrote:

A new compresesor should be able to hold 30 inches of vacuum overnight.

Factory Air or Four Seizens [make] bad compressors. I put a Factory Air compressor in once, and it didn't hold a vacuum at all. It DID have a thick layer of black paint on it, and the paint hid the fact that the end cap wasn't bolted on tightly. In fact, one of the long screws wasn't even seated, not even hand tight!

“88daytona” wrote: “The guy at Polar says that the A590 compressor units fail sometimes by letting the threads corrode in the rear housing causing the bolts to loose their torque value. Then the body will leak, he says it is pretty common because of the aluminum body and steel bolts. The seal and gasket kit was $40.”

Much more information is here on our forums.

Air conditioner upgrades: Myth and reality (by Dan Stern)

There is PLENTY of R-12, and will continue to be for quite some time, and it is NOT illegal. It is, however, illegal for non-certified people to purchase or handle it. Lots of people, myself included, are certified.

Conversion to R134a (the "new" freon) is not necessarily the best option. There are other safe, legal, approved R12 (old freon) replacements that eliminate most of the drawbacks of retrofitting an R12 system with R134a.

There are quite a number of drawbacks to R134a in R12 systems. 134a moves much less heat than 12, which means that your 12 system's effectiveness will be sharply cut, especially when you need it most (stuck in traffic/real hot days). 134a is not compatible with the oil used in R12 systems, and the oil required for 134a reacts poorly with residues that cannot be flushed from a system that has run on 12. This reaction breaks down the oil and frequently destroys the compressor. There are other problems with retrofits.

The best method of repairing an R-12 system is still to repair any problems and use R-12. The cost-per-pound savings of the less-expensive R134a are more than eaten up in changeover service work and reversed in failures that are almost guaranteed to happen.

You might get a mechanic saying that conversion to 134a is just a matter of vacuuming the system and running-in a charge of 134a. RUN.
Or, you might run into someone who wants to replace your R12 with "FR-12" or "Freeze-12" or "Frigc." These three (and several others) are simply 134a with an additive that makes it slightly less violently incompatible with mineral oil. RUN.
You might also get someone who wants to put OZ-12 or HC-12 into the system. These two are blends of isobutane and isopropane. They work very well in R-12 systems, and have no oil incompatibility problems. BUT, they are flammable. To what degree this concerns you is an individual matter.

It's not as clear-cut as you might think, because all refrigerants are blended with oil in the actual system, and ALL refrigerants are violently flammable under catastrophic system breach conditions (refrigerant rushes out, creating aerosol mist of oil--BIG flameball whether it's R12, R134a, OZ-12, or whatever). These hydrocarbon blends also are super cheap (about $1.25 for enough to charge a few systems). BUT they aren't approved by the regulatory bodies for use in auto A/C systems.

Types of refrigerant include:

"Drop in" A refrigerant that can legally be "dropped into" a system with no modifications required whatsoever. No unique fittings, no oil change, no hose change, no label change. Drop-ins exist ONLY for zero-ODP (Ozone Depletion Potential) refrigerants that do not contain CFCs (e.g. R12) or HCFCs (e.g. R22). This leaves refrigerants that contain HFCs (e.g. R134a). There is a high-performance drop-in for R134a, called Autofrost X7 (GHG-X7).
"Substitute" or "replacement" refrigerant: A refrigerant that can be used in a system originally designed for something else, subject to "use conditions."Typical Use Conditions include:

installation of adaptor fittings. EPA wants every refrigerant to have unique fittings to prevent cross-contamination...this rule was made based on heavy lobbying from 134a industry with a heavy financial stake in having NO alternative to 134a.
Installation of barrier style hoses (necessary with ALL non-12 refrigerants, because the other molecules are much smaller and will permeate (not leak) through the older nitrile hose material. An industry is springing up in "rehosing" existing hoses with new hose material that has a nylon barrier. Good idea anyhow.

Have lines rehosed once with a good barrier material and never worry about them again. Also get a better-than-OEM front seal in the compressor. I forgot the name of the company that makes these, but they make really nice all-proof front seals for just about any compressor out there at reasonable prices. Just like hoses, just as well--OE front seals aren't great on the typical C171 compressor used on many CC products. Also must have neoprene (blue) o-rings in system instead of old black ones, but no problem (same O-rings as used in 134a systems) all this sounds extensive, but not really. Rehosing= the most involved part.

Always use a new filter-drier (accumulator)!

Discussion and alternative automotive refrigerants

SnoMan wrote: Duracool, OZ12a, ES12a and HC12a and R12a (to name a few) are all the same product marketed under different names and nothing more. It is considered a flammable (so is gas and your car has a lot more of that in it) and so is not accepted by the EPA. All freons are flammable to some extent and R134 will auto ignite around 400F at 5 PSI if oxygen is present so this flammable thing is debateable and R134 is very toxic when it burns. "AutoFrost" is also know as R406a and it is made up of three differnt components, 55% R22, 41% R142b and 4% Isobutane (a hydro carbon that is very flammable). It should not really be used in a car system without upgrading the hoses because R22 in not compatable with hoses on cars designed for R12 and they will degrade with time and react with the R22 in AutoFrost. This is not a problem with EC12a like knock offs.

The government/military will not certiify AutoFrost for use in vehicles because of the hose issue and it is not a good choice for low dollar conversions unless all hoses are upgraded as well and then it is no longer a cheap conversion.

KOG wrote:

R22 is a theoretical problem in car systems due both to hose and seal compatibility issues. So is 134. But experience has shown that use of these refrigerants in older R12 systems works due to the hoses being oil soaked enought to minimze leakage. Hose replacement isn't out of the question either. Seals are another matter, but that doesn't seem to be an issue with Chrysler systems to date.

R22 is an excellent refrigerant for A/C purposes. You'll find that all window units and most central household systems use R22. The main reason that car systems didn't use R22 in the past was seal compatibility. Otherwise its temperature/pressure characteristics are ideal for the A/C application.

Marcos:

I put Autofrost in my Lebaron about three years ago and have had a good experience so far. No leaks or degradation in performance, and when the outside temp is over 90°F, autofrost cools better than R12 did in this vehicle. Below that, performance is the same. At the time I converted, I had to take out the HVAC housing, to repair the mode-door shaft, so I replaced the evaporator. I also replaced the hoses with barrier type and put in a new receiver/drier.

I did a lot of research on A/C that spring/summer (I am not a tech) and selected Autofrost as the best alternative. According to the Chrysler retrofit procedures and performance charts, a retrofitted 89-90 Jbody would be capable of 51-70° vent temps at 90° ambient, and 59-79° at 100° ambient (a 91-93 retofitted J body is capable of 44-55° and 50-62° vent temps at those ambients) and requires a compressor change as part of their procedure. Autofrost cools well below that with the original compressor still running strong. If I ever have to service the A/C system again, I will probably stick with Autofrost, or maybe try an HC refrigerant, if they do as well at higher temps. I may also switch my jeep (an original R-134a system) to an HC refrigerant. Although it cools okay, it doesn't get as cold as newer A/C systems.

As it was explained to me, Autofrost and other blends have the potential to cool better than R12 because they are composed of multiple ingredients with different boiling points. In the case of autofrost, there are really 2 components; the isobutane is for oil circulation purposes.

In the condenser, the hot, compressed refrigerant vapor enters and begins to drop in temperature as it travels through the tubes. This sheds some heat. Temperature decreases to the boiling point, it begins to condense into a liquid. At this point, the temperature does not change, but a great deal of heat energy is shed to the airstream. After it condenses, it continues to travel through the tube, dropping in temperature, and shedding some more heat. In a serpentine condenser, as my Lebaron has, the area where the phase change occurs represents a small portion of the total surface area available to reject heat.

With Autofrost (and similar for other blends), the 2 components have 2 different boiling points, this creates a "glide" that stretches out the point(s) of condensation over a much larger surface area than a single refrigerant. Increasing this surface area helps give the system a greater capacity to reject heat to the outside air flowing through the condenser.

A similar feat is accomplished by switching to a parallel-flow condenser. Parallel flow condensers are often employed to increase cooling performance of an r-134a system (either OEM or retrofitted). They can be pricey, however.

It is currently illegal to buy or sell R12 containers under 20 pounds to/from unlicensed people.

EEK! Air conditioners (by Lane MacFarlane

I have quite a bit of personal (!) experience on the A/C on 1982-1988 L, K, and S bodies (having or having had a 1982 Turismo, 1988 Aries Wagon, and 1985 Voyager, and having had to replace evaporators on all three!). All of the above (2.2 or Mitsu 2.6) used a Chrysler/Nippondenso C-171 compressor. This is a dual-acting 3 piston/6-cylinder swashplate type compressor with no pressure controls (EPR valves, etc.). I understand there's a variant of this compressor with variable displacement on some '90 and later vehicles (I remember a 1990 Voyager/3.0 Mitsu had one).

There were two basic variants to the early C-171, with only the mounting changed. One was the "soft mount" that's on my 82, and it uses rubber isolators and a sub-cradle to mount the compressor. The other was the "hard-mount" that was on the 88 Aries 2.2. The 2.6 and 2.2 "soft mount" compressor appear to be the same (they're the same number in the 4-Seasons book, at least), even though the 2.6 mount is different.

My 1982 has its original compressor and clutch (85K miles), the Aries still has its original compressor (110K miles and another owner), but a second clutch, and the Voyager is on its third compressor (original went out in 1986, that one started seeping oil from the center O-ring in 1996). The basic compressor appears to be quite sturdy, if treated right (don't let it run without oil!), if the system is kept clean (always flush the system if you replace the compressor), and if the rebuild job is good (for a rebuilt compressor, of course).

The real kicker is the quality of the rebuilder, and there's no way of knowing that until the rebuilt compressor crumps! My rebuilt C-171 for the 85 Voyager 2.6 was $110 at AutoZone, no clutch, no problems yet (2 years).

The belt tension appears to be critical, especially on the dual-belt arrangement on the 2.6 (I've gone through two clutches, both having had the bearings destroyed). If in doubt, keep it on the loose side is my advice. As for the system hoses, they're all junk (IMHO!), and should be replaced when the system is opened up, with good quality barrier hoses with really well-crimped ends. Now, as for later A/C systems, my knowledge stops at 1988. Cheers!

Additional historical and R22 notes (Mike Sealey)

The earliest Chrysler trunk mounted A/C systems used R22. My theory is that since Chrysler's Airtemp Division made home and commercial A/C units already, this is what they were familiar with and this is what they used. A/C units from 1957 on appear to have used R12, and were sourced from an outside supplier (Eaton, Yale & Towne in most older models) despite use of the Airtemp name. In fact, some 1957 MoPar owners' manuals refer to the factory A/C units as "Cartemp Air Conditioning", an apparent attempt to establish a secondary brand name for the outside-vendor-supplied car units.

This turned up in a thread on the Online Imperial Mailing List about five years ago or so, when an Airtemp-equipped 1953 Imperial was found to have markings of some sort calling for use of R22. I believe the Howard Hughes 1954 New Yorker used a much tinkered with version of this unit - some sources say Hughes' air purifier cost more than the entire car!

1953 was apparently the first year for A/C in Chrysler vehicles, although they almost had it eleven years earlier. Auto A/C first turned up in a small number of 1941 Packards (at least one source says 1939), and DeSoto had actually catalogued A/C as an option for 1942, but none were produced as a result of World War II and the shutdown of passenger car production that followed.