Matt O.

I'd like to finally fix my A/C. Generally, I do not drive the 951 in anything other than 72F weather... but that should prove to be rare here in Texas.

The A/C has not worked since I purchased, I knew it when I purchased it. Was not a concern.

My question is, I would like to keep the originality of the R12 system, if possible, vice converting to R134. Is this possible in 2011? I have read about R12-type refrigerants, are they effectively "plug-n-play" into the existing system? I imagine I need to rebuild with new seals, dryer, etc.

Thoughts?

Matt

JohnKoaWood

You should be able to have someone service it with R12, however be prepared for the price!

SeaCay

R-12 is available all over the place (see eBay), that's not your issue. You may run into issues finding a competent mechanic willing to work on your system. The rubber hoses connecting the various hardlines may also have problems holding a charge over time. You can remove them and get new rubber hose swagged onto the aluminum tubing, but it's a major PITA to get all of the hardlines out with the engine and ancillaries in place.

86 951 Driver

Just like above said. The equipment to keep it R12 is expensive. You could get a cert from the EPA, a set of gauges, and R12 to try and refill it yourself. Not sure how well that will work. Didn't work for me, but you might be lucky.

Why are you wanting to keep R12?

Landseer

Where in Texas?

944hal

I got tired of trying to top the R-12 in my S2 each year. I just converted it to R-134 a couple of months ago. I'm lucky that I have a mechanic I trust to do the work I don't want to do or have time to do. It cost, including parts, labor and R-134 approx $250. It cost half that much to top off the R-12 last year. It's been mid 90's here in GA the last month. Black on Black S2 stays COOL.

Mark Hubley

I'm no AC expert, but fellow Rennlister "pnbell" and I fixed up our AC systems a couple of Saturdays ago. I've got a 924S and he has a 944 ('87 I think). Both of us are now running R134a.

I more-or-less followed what is written in this Porsche TSB: http://academic.pgcc.edu/~mhubley/Porsche/aircon.pdf

The only thing I replaced was the receiver-dryer. My system was basically empty, so there was no R12 left. (My system held vacuum just fine, but after 25 years and little use over the past 15 years, the R12 found its way out.) I used some AC flush I got from Advance Auto to clean out the condenser. Then I added PAG-46 oil (basically the equivalent to the ND-Oil 8 referenced in the TSB) and R134a. It's only been a couple of weeks, but it's been hot enough here in Maryland, and so far so good on the AC. Nice and cold.

Anyway, I think any time you do major service to the AC you may as well replace the receiver-dryer (and its seals). The key point here is that according to the Porsche TSB, the switch to R134a doesn't really require any changes other than the oil and the R134a.

Mark Hubley

Oh yeah, it cost me about $90 for the refrigerant, oil, and little retrofit thingies to put on the service ports. Everything was available at Advance Auto. Peter had the pressure manifold and vacuum pump.

Landseer

Yep. Easily done in 12 or 134.
Especially if you inherit a system that some yahoo hasn't cracked open.
944/51/28 have fantastic compressors.
Working air really adds to the value and desireability of the ride.
Some excellent DIY info exists on the 928 forum, though probably exists here in the archives as well.

Must haves are new expansion valve, all O-rings (including at top ports of compressor), drier, correct oil for the charge @ correct qty in millileters, new schrader valves. Flush condensor, lines and evaporator.

Quick jumper of low pressure safety switch at compressor will tell a lot --- hope it spins without noise. But only for 10 seconds or so --- don't stress it.

Then attack the overall refresh/fix. Very satisfying.

Matt O.

Good gouge, thanks alot!

86 951 Driver

What kind of adapters did you get? What o-rings did you replace?

SeanR

If you will take the time to change out all the other stuff, such as hoses, seals, drier etc. Bring it down here and I'll fill you up on R-12

Mark Hubley

I replaced the O-rings that go where hoses hook up to the dryer (drier?), and I replaced the dryer.

The system has a port on the low-pressure side of the system and a port on the high-pressure side of the system. The ports allow you to hook up a pressure gauge and add refrigerant. The ports on an R12 system are different than the ports for an R134a system. Most auto parts stores have fittings for R134a that just screw over the R12 fittings. They cost about $12.

My original compressor seems to be working fine, and I did not change the expansion valve. Perhaps that's taking shortcuts, but so far so good. My car is not a daily driver. If something fails, then I'll deal with it at that time.

M758

I was driving my 951 yesterday. 113F and my stock R12 A/C system worked fine. I am not even at a full charge as I have some air bubbles in the system. My A/C had been down for 2+ years, but that was due to a bad relay and me being too lazy to track it down. It still holds a charge on 20+ year old parts.

I plan to keep my A/C R12 as long as possible.

Matt O.

Thanks for all the data. That's what I'm looking for -- what parts to replace to keep as much of the parts original and top off with R12.

Sean I will probably take you up on that.

Matt