R12 to R134a conversion - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 08-03-2003, 09:51 AM   #1
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Default R12 to R134a conversion

I had an air conditioning system problem on my 92 SSE :( . Thanks to the Auto Climate Control Diagnostics I found here, I was able to determine I was out of Freon. After checking a few places for prices on a recharge($50 lb +labor, here in Atlanta), I checked on retrofitting the system to R134a. The cost estimate there was about $300. Still way over my budget for this summer. Anyway, while in my local NAPA parts store I saw a R134a retrofit kit($37). The guys there says they work fine. You get a valve with hose and new fittings and 3 cans of R134a. I went down the street to Advance Auto, and viola, same kit was $29. They informed me they were selling alot of these. I bought one, there was no Freon to remove, so I added 3 cans of R134a with oil and I have COLD air again. Just wanted to let those who haven't tried this, that it works! I don't know if there will be any long term effects, but for the past month, I've been cool.
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Old 08-03-2003, 06:23 PM   #2
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FYI on the 134a freon, I was once told by a mechanic that 134a systems are great but have one bad side effect, they tend to leak because the molecules are smaller then the R12 system. He told me to prolong the life of the freon I should shut off the AC in the car before I turn the car off. He said that would depressurize the lines a bit better so that when the lines cool and shrink they won't let as much escape.

Not sure if thats all entirely true or not but I do notice if I don't do it my car hisses after i shut it off and the AC has been running.
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Old 08-04-2003, 02:15 AM   #3
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yah my dads truck uses R12 and its so friggin expensive....i just fixed my air conditioning (134a system) and it turned out to be a loose connector between the lines....i was happy i could fix it myself and not have to pay over $100 or some crap like that to get it fixed works awesome now.....
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Old 08-04-2003, 02:06 PM   #4
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Quote:
Originally Posted by JrFaust
He told me to prolong the life of the freon I should shut off the AC in the car before I turn the car off. He said that would depressurize the lines a bit better so that when the lines cool and shrink they won't let as much escape.

Not sure if thats all entirely true or not but I do notice if I don't do it my car hisses after i shut it off and the AC has been running.
No, that has nothing to do with anything. When you switch off the car, the compressor stops; if you want to turn off the A/C first, then the compressor stops sooner, that'* all. The A/C system itself couldn't care less what order you do it in, and there are no other A/C components that keep going after you switch off the compressor and before you switch off the engine.

The hissing or wheezing noises you hear after shutdown are due to the pressures equalizing between the high- and low-pressure sides; it'* normal.
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Old 08-04-2003, 02:14 PM   #5
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Quote:
Originally Posted by jr's3800
This is the incorrect way to do it but it has worked for me...
It doesn't sound incorrect at all; the latest info from the EPA is that you can indeed do a closed-system conversion to R134a as described here.

There are only two things I would mention, though:

1) It'* a good idea to get the system evacuated first anyway, since that will tell you if there are leaks or not. (Over the _long_ term, measured in years, it'* normal for the refrigerant to leak through the hoses.) If it can't hold a vacuum for a few minutes, it ain't going to hold your refrigerant much longer than that.

2) There are two different error codes for Freon loss, if I remember right: a leak error and a long-term loss error. If it'* a long-term code, that'* more or less normal for the age of the car. If it'* a regular leak error, you may have a hole in the system. If yours is a typical Bonneville, the most likely place for that leak is the A/C evaporator (especially if you don't have much airflow from the ventilation system inside the car; the oily, leaky evaporator clogs with dirt and blocks the airflow).
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Old 08-04-2003, 10:16 PM   #6
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Any charging of an air conditioning system should only be done following the correct procedures. Undercharging or overcharging will cause higher vent temperatures and other problems. The selection of compressor oil is important for a retrofit. Don't use PAG oil with old mineral oil in the system. If the R-12 leaked out, so will the R-134a.
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Old 08-04-2003, 10:33 PM   #7
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Quote:
Originally Posted by acg_ssei
The hissing or wheezing noises you hear after shutdown are due to the pressures equalizing between the high- and low-pressure sides; it'* normal.
Thanks now I won't kick my self every time I forget to shut it off.
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Old 08-04-2003, 11:17 PM   #8
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Quote:
Originally Posted by jr's3800
Quote:
Originally Posted by acg_ssei
If yours is a typical Bonneville, the most likely place for that leak is the A/C evaporator (especially if you don't have much airflow from the ventilation system inside the car; the oily, leaky evaporator clogs with dirt and blocks the airflow).
Thanks for the info Andy
Hey, wait until you see the _pictures_! Old and new evaporators side by side: it ain't pretty.
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Old 08-05-2003, 06:39 PM   #9
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Cool, so if I convert to the 134 I can just let all the R12 out into the atmosphere and then start with the new !!!!

On a more serious note, one way to get around the evacuation issue is to put maybe one can in, and then let it out, in an attempt to flush the system a bit.

Is it possible that I may be somewhat low on freon without getting a code? I think it should be colder than it is.

Thanks,
Steve
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Old 08-05-2003, 11:04 PM   #10
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Pressure gauges are the best way to check the A/C for proper operation.
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