W.Bruckner

A/C hasn't worked for at least 15 years on my 968, never bothered to have it recharged or attempted to fix it. I'd like to give it a try now. I'm getting a replacement compressor. What other parts would common wisdom have me replace in the process? Receiver drier?

tempest411

Yes, absolutely the receiver drier. Before taking anything apart you'll want to test the system for leaks. Once you take the caps off the ports on a new receiver drier you're on a countdown to get it installed, the system evacuated, final leak-tightness confirmed, then back-filled with refrigerant. If you leave a new receiver drier open to the air too long it will absorb moisture, rendering it useless...or so I've learned.

audi49

I did the following when I upgraded my system to R134a (on a 944 base).
Dissassembled/flushed, replaced expansion valve, replaced all o-rings, replaced dryer, installed reman compressor, added ~6 oz of oil (per Griffiths). Pulled vacuum. Charged with R134a.
The o-ring replacement is tedious, but can be done.

Chalt

I think the best approach would be to figure out why it doesn't work and then make a plan on what to do next. Is the system completely empty of refrigerant? If so, was it an O-ring leak? Did the fittings or hoses leak? Did the compressor leak at the shaft seal? You can pressure test it to find out. If there is still refrigerant in the system, what failed? Compressor? Pressure switch? AC module in the dash? Other electrical-related failure?

There is a lot of reading material out there on AC work. One thing you'll need to pay attention to is to drain the old compressor's oil and determine if the system has contaminants, like from a black death compressor failure. If there are contaminants in the system, it will have to be flushed, which can be an involved process. If contaminants aren't removed, the new AC system may not last long.

I would replace the compressor, the drier, any o-rings, compressor to condenser hose assembly, and switch from a tube-and-fin condenser to a parallel flow condenser. The condenser swap isn't mandatory but a PF condenser will exchange more heat, making the system work better and cooler temps at the vents.

Griffith's has a kit with all of that stuff (not the condenser), and they have good feedback from the community. I am not affiliated.

All of this said... Some have rebuilt the original Nippondenso compressor and had success. Some leave the original condenser. On the condenser, the hotter your climate, the more you would benefit from a parallel flow unit.


Here is a very well-done video of a R-12 to R-134a conversion on a 944. NC944er makes awesome videos related to 944.

ElRicardo

Aud49, could I hear more about how you accessed and removed the two hoses (hardlines at that point) that go through the firewall? Also how you accessed the expansion valve?

audi49

Yes, those are both challenging.
First, for the two lines through the firewall. I removed the bolts that hold those connections together from the top, with small tools and a lot of patience. When I reassembled these connections I realized a much easier way to get to them is with a long extension between the exhaust manifold and the cam cover, wrenching from the front portion of the engine. Hope this makes sense. Helps to have a visual of how those connections work. Many links online to help understand that.
Second, I got to the expansion valve by removing the plastic blower cover. It's under the black goopy stuff that you see in the photo below.
Hope this helps.

Chalt

A few questions:
1) Did you do all the repairs with engine-out or engine-in?
2) Did you remove the hard lines or just disconnect them? This was to flush them, right?
3) That expansion valve looks hard to get to! Were you able to replace it from the access point you show in the picture?
4) Did you have to take the dash apart to do any of the repairs?
5) Did a lot of crud come out of the lines when you flushed everything?

maint

As to why the AC wasn't working...
I went through 4 compressors [ resealed, rebuilt, used and new] before a AC specialist explained why. The other shops just refilled or said replace compressor. My car sits for most of the winter and the nose seal ( graphite )dries out. When it is subsequently started the dry seal tears itself up then leaks. I have been without AC for a few years but am thinking of trying again as this winter I set my phone to remind me to start the car every two weeks. Ran much better after doing that and it would be easy to just leave AC 'on' for the winter start ups. Recently got a Sprinter that had sat for a year; had AC for the first test drive and none afterwards. Shop says nose seal is destroyed so I'm a believer.

Chalt

What Is a nose seal? -- Found the answer... It is the compressor shaft seal. It is true that you should run the ac every month of the year to keep seals from drying out. I do use the AC year round in my daily drivers (Civic and Silverado) for defrosting the windows when they fog up. Having to start the car every two weeks would be good for it in many ways, but I wonder if your car didn't have other sources of leaks besides the shaft seal. These cars are old and it wouldn't be wild-thinking to imagine that there could be other areas in the system that have small leaks. O-Rings don't last forever and there are a lot of places an ac system can leak. If there are contaminants in the system from a compressor failure that don't get flushed, those contaminants will continue to circulate through the system and in short order tear up the new compressor.

goblues38

Well...based on this thread and nc944er video...I have purchased all the parts....looks like next weekend I will try and get the AC working in my 1990 944 cab

when it is 105 degrees and 90% humidity , some ac with the top down is welcome

Chalt

You should start your own thread and document it. That is, if you want to. If you do though, it would be helpful to everyone in the 944 community. In any event, congrats, and we would like to hear how it goes for you.

audi49

Answers, to the best of my recollection. (I'm presently traveling and don't have my notebook in front of me unfortunately).
1) Did you do all the repairs with engine-out or engine-in? Engine in.
2) Did you remove the hard lines or just disconnect them? This was to flush them, right? I disconnected the hard lines, but did not remove them. I wanted to replaced all the o-rings, hence disconnecting. I did replace one of the flexible hose lines as I had a real hard time disconnecting one of those hoses from the condenser and therefore had to tear into the connection.
3) That expansion valve looks hard to get to! Were you able to replace it from the access point you show in the picture? Yes, I was able to replace it from there. It wasn't hard to get to at this point. I was a bit of work to remove the plastic housing, and then reseal the housing upon assembly.
4) Did you have to take the dash apart to do any of the repairs? No
5) Did a lot of crud come out of the lines when you flushed everything? No, I was surprised how clean it looked. I rented a canister thing from autozone, with compressed air from my compressor to flush. I don't recall exactly but I flushed in segments of the system.

ElRicardo

I swear reactor #4 at Chernobyl is more habitable than a black top-black interior cabrio without A/C on a hot summer day…

Chalt

Thanks Tom! All this info is valuable to all of us working on 944 ACs.

goblues38

My top is only up in winter. we take our last drive early October, and the car sits till march. By fixing the ac system may be able to drive the car some in summer with he top up.