A/C Conversion to 134A
 

Question? Anyone switch there R12 to R134A? The Porsche tech bulliten for the 1985.5 and up requires ND-Oil 8 (pretty common stuff) and a new Dryer. I have a freon handler license and can purchase R12 here in Colorado, but the stuff is $35 a pound and becoming scarce. From what I can tell the ND Oil uses a conditioner to inetract with the newer type 134A oil to keep the seals in good shape.

hi, i jsut did mine on a 87 951 with one of the kits from autozone, it seems to be working well, altho its only been like a month, i didnt change the drier jsut because i wanted to see if it would work without changing it first, the fitting on my car is right on the compressor. The kits contain a can of oil which i assume it the same stuff u r talking about, correct?..jeff

I've mentioned this before. In 1997 I put a hydrocarbon substitute in mine which is mostly propane. It has worked well. Of course, the stuff is flammable but so is gasoline. Just charged the old thing last weekend. Propane, thermodynamically, is a better refrigerant than 12 and especially 134. Email me if you want address where you can buy stuff. I do not sell it nor do I gain anything from others who use it. I use it in an old MB and my track car.

Be carefull with a 134a conversion. You'll need to get as much of the r12 mineral oil out as you can. Then make sure the new oil is POE and NOT the PAG oil that was originally used with 134a. PAG oil will react with the residual r12 chlorides on the system walls (which can't be removed with flush) which will break down the oil, create acid, and you'll have a failure in a couple months.

Then pull a really deep vacuum for at least an hour, but I'd go with three (on a hot day with engine hot) before you add refrigerant.

Since, IMO, the r12 ac on these cars isn't all that powerful in the first place, you might be disappointed with the cooling after even a successful conversion. R134a will always be warmer than r12, especially if you don't put in a bigger condensor (which is not really an option on these cars.)

I'm using Autofrost (R406a) www.autofrost.com, and am very happy with it. It's $10 a can. Only downside is if you already have a small leak, it will leak faster with Autofrost because of the smaller molecule. And because it's a blend of several refrigerants, you'll need to totally evacuate and vacuum if you get low on refrigerant because the blend % will change as they leak at different rates. But hey, I don't mind doing it once or even twice a year at only $10 a can.

Try this site. It has a lot of good info on the 944 A/C system.

http://members.tripod.com/prsch944/



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-Dave-
1984 944
99 days and a wakeup.

I did this conversion on my '79 924 3 years ago. First, don't use PAG oil, use POE. It's completely different. It's also what is supplied with the kits from Autozone. I went the cheep way and just used the kit (1 can of seal conditioner/oil; and fittings). It worked just perfectly. The air comes out at 40 degrees without recharging. I also did thin on my Caravan and Eclipse. All work fine.

where do you get a vacuum pump that you can hook up for 3 hours?

is this like a mechanical vacuum pump that runs like an electric tire pump, or do you just use a hand pump and pump it up and leave it?

No, it's a compressor based vacum pump that I purchased from Harbor Freight for $12. You need 90psi regulated.