A/C Systems--R12 vs R134


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Old 01-04-08, 02:38 PM
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A/C Systems--R12 vs R134

I'm seeing a lot more used car ads for cars that are less than 10 years old with normal mileage that say "a/c compressor replaced" or "a/c not working" or similar language to indicate problems with the a/c system. Are a/c problems becoming more common on cars these days? Could it be the new R134a refrigerant? I've read that R134 A/C systems in most cars after about 5 years have high failure rates because they run at a higher pressure and are not as cold as the old R12. It seems like more domestic makes have problems than imports regarding air conditioning, from the ads I read. I remember driving 80's GM cars with R12 that would freeze you out and last a long time. What are some late model cars with good or problematic air conditioning? I'm basically after a reliable low mileage peppy/good torque for around town midsize sub $3000 car with an ice cold A/C system. Should I stick to cars with the old R12 system or ones with brand new a/c systems installed? I've usually found good luck with 1986-1991 GM A-Body (Pontiac 6000, Olds Ciera, Buick Century) and 1986-1991 H-Body cars like the Olds 88 and Buick Lesabre. Thanks in advance for your advice/opinions.
 
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Old 01-05-08, 10:42 AM
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One vs the other, I don't think you have much of a choice. The R12 system is essentially out and linked to cars that you wouldn't be able to maintain because of parts availability, either in general upkeep or the AC system.

I converted my Toyota from R12 to 134 about ten years ago. All I did was take out the R12 and put in the 134/oil and the AC has been fine. Most would tell you the compressor should be fried by now, but it works very well.

What you've heard about the new systems (134) may or may not have some substance. I haven't any first hand experience with any problems.
 
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Old 01-06-08, 08:37 AM
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You're right about higher pressures and loss of efficiency when the industry moved to r134, but I can't comment about reliability. I just assume that if you buy a new car, the a/c will give out in 5-10 years for any number of reasons. In fact, the only car I bought new - an 85 Omni - I ordered without a/c because I didn't want the complexity under the hood nor the expense of repairing it later on.

Even if you find a car with cold working a/c, who knows how long it'll last, or whether it was patched with stop-leak and recharged for sale. A/C is a real crap-shoot when buying a used car. I wouldn't make it a priority for your purchase.

Conversely, many people will sell an otherwise fine car because they see that the estimate to repair their a/c costs more than the car is worth, yet they really want a car with working a/c, so they buy a new car. These used cars are an excellent buy for the DIYer who knows how to repair a/c systems. DIY a/c repair is one of the most financially rewarding repairs one can learn to do.
 
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Old 01-07-08, 03:48 PM
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Thanks for the info. I live in Arizona, where it's A/C weather for 5 months out of the year and temps often go over 110. When a car has been sitting outside, it's nice to have a old R-12 GM Harrison unit to cool you down fast. So in addition to mechanical shape, the condition of the a/c is important for us here. Would having the a/c system inspected by a technician reveal anymore info about the a/c system?
 
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Old 01-07-08, 04:57 PM
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I can appreciate the must-have a/c situation in the South. I don't think it's worth the tech's time to check out an a/c system. He can check the pressures, vent temps, and look at the visible condition of the system (i.e., leaks at connections, noisy compressor), but he won't be able to tell you how long the system will last, which is what you really want to know.

If the car blows cold at the time of purchase, that's the meat of it right there.
 
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Old 01-08-08, 05:40 AM
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r-134 works jusr as well as r-12 did...i have a 2000 chevy tahoe that will get cold enough to hang meat in.

i think what you are seeing is the movement toward lighter weight and more cheaply made compressor units. bcak in the late 70's and all through the 80's we saw LOTS of compressor failures with radial (R-4) GM compressors because they were doing more work with less compressor. the days of the heavy weight A-6 compressors is gone, never to be seen or heard from again. in fact, it won't be too much longer til we start seeing the next generation of AC and that will present consumers with a whole new challenge. it's weight and environmental concerns that drive these changes past and present...the next generation...CO2. way WAY higher pressure, solid lines (no more rubber hoses) but a safer more environmentally friendly gas...

As far as a used car with a great ac...listen for any strange noises when the compressor is running, make sure the blower works on all speeds and that there is sufficient air volumes from the ducts, check to see if it has the original compressor. a replacement means that the system has been opened and there are several red flags asscoiated with a system that's been opened. depends on whether the work was done by a competent and concientious ac tech or not...

also, give the system time to get working well...stabalized before you judge it's performance. my experience has been that an older higher mileage vehicle will take a little longer to get to that point (wear and tear). my truck still gets ice cold...but it doesn't get there as quickly as it did when it was new.
 
 

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