A/C Conversion-What's Involved?

snipped-for-privacy@yahoo.com wrote in news:7c7de3ab-48c1-4004-af73-2f79137e3d28 @m36g2000hse.googlegroups.com:

If there's no leak, don't convert! Just get it recharged with R12.

Automotive A/C systems naturally leak roughly an ounce every year, so a system with one pound of refrigerant will be at zero pressure after roughly

16 years even if there is no actual "leak".

Have your garage check for leaks before anything else.

Depends. You can do it right, half-assed, or screwy. The right way involves changing the evaporator coils, cleaning the whole system out, draining the oil out (often involving pulling the compressor off), adding new oil, pumping it down, and repressurizing it. The half-assed way involves cleaning the whole system out, draining out all the old oil, putting in new oil, pumping it down, and repressurizing it. The screwy way involves putting new oil in and hoping that most of the old oil is already out and that what is left is miscible, pumping it down without cleaning anything, repressurizing and praying.

The cost difference between these three, both in parts and labour, is substantial. Oh yes, you also need to fit on new fitting adaptors in all cases, and I'd replace the dryers just in case....

--scott

You would probably be better off staying with R12. Just have any actual leaks repaired and recharge. The price of R12 has come down a LOT.

I did it with my 90 Buick Reatta.. Nobody here even stocks R12 anymore. Some will put in a can or two of refrigerant blend, which may work, or may make things worse.

In my case I had to change the compressor anyway, because the old GM pos was leaky around the seal.

Since there were no other leaks, I flushed the black death out of the system, replaced the R12 fittings with 134a ones, replaced the accumulator (filter drier).

It was done correctly, and the parts ran me about $300-400

One other item. Since R134 isn't as efficient as R12, the condenser size needs to be increased to match the cooling capacity of R12. This can cost a small piece of change. Of course you can omit this step and bear with the decreased cooling capacity. I'm not really aware of the % of difference and it may very well be transparent to some..

It was not necessary to replace the condensor, and the car works fine with the new conversion. Do it if you wish, but IMO it is not necessary.

On Sat, 19 Jul 2008 12:48:28 -0500, "HLS" wrote:

What works well may depend on the car/system. About 7 years ago I took my 1990 Corsica 2.2 to my mechanic when I was using him for my car work. Wanted a shot of R12 because the cooled air had warmed up a bit. He suggested he convert it to R134, and said he'd do the whole thing for a little over $100. Just change fittings, evacuate the R12 and refill with R134. I mentioned reading that you needed a new compressor, hoses, blah, blah, and he said he'd had good luck just doing the fittings on this system, and there was little to lose. Think he charged me @$120. Worked good the rest of the summer, the next summer, and almost the whole third summer. Then I came home from work one day and heard hissing as I exited the car and saw an expanding oil spot on the street under the condenser where the hissing was coming from. Could well have been a stone bounced up on it and holed it. Don't know. Never bothered doing an autopsy on it. Might have been a compressor failure put undue pressure on a weak spot in the condenser, but I don't know enough about it to say. It was blowing cold until that moment. Since by now my kid was gung ho to fix anything automotive, had a gauge set, evac pump, etc, I popped for a new condenser and he put it on. Big mistake since it turned out the compressor was shot too and I didn't care enough about A/C on that car to buy a new one. So that car has been running around the last 4 years or so with a $300 new condenser but no A/C. Yeah, yeah. Seems a waste, but I'm a firm beleiver in not throwing good money after bad. I've never missed the A/C much even on hot days. Around here (Chicago area) you might use it 30-40 days a year, and I don't wear a suit any more so it's no big deal. The car I take to Florida is the one that really needs A/C. The kid is coming over today to a do final strip of the '93 Corsica

3.1 he's junking and said if the bolt patterns match he'll throw the '93's compressor, which works fine, on the '90 just for kicks. I've noticed some difference in the air temps between R12 and R134 on GM cars, but if the R134 system is performing correctly it doesn't matter much. The only difference I notice is that with R134 women don't bitch as much about their arms getting cold. I posted recently about travails fixing my '97 Lumina A/C, which is fine now, BTW. My biggest advice where I know exactly what I'm talking about regarding the GM systems as used on the '97 Lumina et al is: Buy new OEM compressors only. The price diff over a reman just ain't worth the risk of redoing everything. In my case TWICE. Don't trust Murrays Auto Parts to have A/C o-rings on the dryer/receiver they sell. The R134 went through their supplied o-rings in a couple days.

--Vic

Could be true. I bought all my parts from

These are good people with a wealth of information.

If your "mechanic" switched refrigerants without washing out the system and adding compatible lubricant, you were doomed to problems.

You dont necessarily have to have a new compressor (unless the old one is crappola like mine) but you DO have to use compatible lubricant.

You dont charge 134a and 12 in the same ratio either.

On Sat, 19 Jul 2008 17:16:14 -0500, "HLS" wrote:

My mechanic was good. His shop serviced mostly gray-haired guys driving well-maintained GM's. Wouldn't throw parts at a car and everything he fixed on mine stayed fixed. I sort of miss talking to him since my kid started taking care of the cars. But he also instinctively knew how much money to throw at a 12 year old Corsica. I wouldn't insult him by asking if he knew he needed PAG for the conversion. And like I said, I got my money's worth out of it. The problem with the whole washing thing is how good it works. The ackits site info on flushing is an example, where they say it might not get the condenser clean and you should replace it. But there's no way in the world to know if you got the condenser clean. If you go by the "A/C Pros" selling you stuff, you'll just replace the whole system when a compressor fails. Not that flushing isn't a good idea, just where you draw the line. I've only replaced a couple compressors, so I'm not claiming I'm an expert. One was an R12 on a 350, no evac, a shot of oil, and it blew cold for about 4 years until I junked the van. Now this R134 Lumina I've posted about. I mentioned it was evacuated for each of the 3 compressors we put on after the originals seal failed. The kid took it to his shop each time, where he has his pump. When we replaced the dryer o-rings in my garage we didn't evac. Would have preferred that, but frankly was getting sick of dealing with the thing, and the kid had just gotten his new used car and I knew he didn't want to take the Lumina home and to work again. Not too worried about it. Also curious to see if the kid's old compressor works on the Corsica. Nothing to lose but 20 minutes of wrenching and a couple cans of R134. Hey, I always liked the looks of those Riatas and was thinking about getting one. 2.8? How did you set up the flush system for the A/C?

--Vic

Believe me, you dont want a Reatta. These were pretty cars, very comfortable to drive, but were a pain in ass in every other aspect. The electrics were terrible. GM should have had the death sentence for them.

You can buy mine for $2-3000 if you want it. Good engine, tranny good, but it IS a Reatta

Friend owns a garage with all the proper AC equipment. I took it over to him and he circulated solvent through the system, then dried it out. It had the original system intact, GM leakomatic compressor. It was nasty.

I'm guessing you're not a salesman (-:

--Vic

Honesty, as much as possible, is one of my downfalls ;>)