mpesik

Hello it's been hot lately and my 87's airconditioner barely puts out.
It has not been worked on or recharged ever.
Would a recharge do it? How much is a recharge?

j.kenzie@sbcglobal.net

Hi,
You need to go through an a/c diagnostic test. You will need to see if the a/c button lights up, if the compressor clutch is engaging and what the high and low side pressures are. The most likely problem is refrigerant loss, but it could also be in the electrical control system including the a/c relay inside the a/c controller. You may have to have a full evacuate and recharge done, with UV dye to help evaluate potential leaks. This should cost $200 or less, depending on the refrigerant, R12 vs. R134. If you have a leak, then the defective component(s) should be repaired or replaced after recovering the refrigerant again. Avoid sealants. These are basic a/c principles, and since special equipment is required you should probably seek a good a/c shop or indie mechanic for detailed advice.
Good luck,
Dave

mpesik

Thankyou for your good advice.

Manfred

Check out this thread:
https://rennlist.com/forums/928-foru...-cleaning.html

Also, does it blow hot all the time? A bad heater valve is common problem that results in hot air mixing with the cold air, even if your AC is working. Do a search on this.

Chances are if it's never been recharged that's gonna have to be done too. It's also likely that you'll have leaks so some o-rings likely need to be replaced.

Lastly, Dwayne did a great write up with pics on testing the HVAC actuators and solenoids. It's very likely that at least a few of the diaphragms in your HVAC actuators will need replacement.

928 Specialists has a good write up on testing the electrical components of the HVAC system (courtesy of Wally). This is good if your AC compressor is not kicking in and running.

WallyP

Decision time. There are two ways to go at this point.
1) Try to find an honest, competent shop to work on your HVAC system.
- Pros: They have the tools, knowledge and certifications to work on auto A/C systems.
- Cons: They can be expensive. Very few A/C shops have the knowledge to work on a 928 HVAC system.
2) Learn to work on your own system, get the tools and certifications necessary.
- Pros: You can do almost all diagnostics and minor repairs fairly easily. You are not paying for someone to learn how to work on a 928. The knowledge carries over to other vehicles.
- Cons: The tools can be expensive, depending upon how deep you want to get into evacuating, leak-testing, etc. You will have to do some serious studying.

If the system has been working for years with no attention, getting it going again might be as simple as adding refrigerant. If you get the required certification, R-12 is still available. No certification is required for R-134a if the system has been converted. Gauge sets are readily available.

While it is an EPA violation to knowingly recharge a leaking system, if you put two 12-ounce cans in and it works for the next five years...

Randy V

Just buy a can of R12 and a guage and hose on eBay and recharge it.

That will get you through the summer.

bigmac

I had to have the A/C on my 90 rebuilt as the were leaks in the system that my local Experts could no fix.
Local Porsche dealer was able to handle
.

James Bailey

And do you mind sharing what the cost of a dealer rebuild was, as well as what items were replaced.

mpesik

Thankyou fella's- you too Randy.

docmirror

First; Turn on the car, and the AC, open the hood, and see if the clutch on the front of the AC compressor is cycling on and off. If not, high failure item is the blown relay on the HVAC head.

If it cycles, go buy a drier/reciever and take the car to an AC shop. Have them evacuate it, then replace the drier/reviever. Test it with vac and if it holds for 15min with very little loss, then they can test the pump and if it's working, recharge with the R-12.

Rich9928p

Here in Arizona good A-C is a must. The greenhouse windows on the 928 in the summer place huge demands on cooling.

My '87 928 held charge for 5 years after I bought it, then at a bit over 100K miles the compressor seal was weak. It was time for a rebuilt compressor and new O-rings. Two years later, it was blowing warm again, this time both front and rear expansion valves showed signs of leakage and were replaced. The pipes to the rear AC were also removed and new O-rings installed. I was hoping that this fix would be good for another decade. About a year later, it was blowing warm once more. This time, a leak was found at the heat exchanger fitting where the A-C line cools the return to tank fuel at the center rear of the firewall. The O-rings had just failed. Well, at over 140K miles she's back to blowing as cool as can be expected in our 110F summer AZ heat.

The lesson learned is anywhere that an O-ring seals a fitting is a potential leak zone. If you haven't had a recent service, once the system is evacuated replace as many O-rings as you can. They can and will fail with age. I'm sure that in more temperate areas O-rings last longer - Arizona is about as bad as it can get for heat soak in the summer.

If your A-C is blowing warm and the leak source isn't found, it will leak and blow warm again. To do the job right - find the source of the leak and FIX IT.

docmirror

Yeah, all the joints are by now nearly perished. If I was going to do the job, I'd do all the o-ring seals just to be proactive. I'm getting ready for this job on my Ferrari soon.

jeff spahn

Note: When you replace the O rings do yourself a favor and slather Nylog on them. Get the version for your particular refrigerant

TheoJ

It is probably the AC... and all is already said.
but one thing that nobody mentiones but does make a difference: if the vacuum system is leaking you will have airflow issues under the dash as all the vents have vacuum operated flaps. If there is a large vacuum loss the heater valve will not even close properly. Both will make a perfectly good working AC turn into poor results.
There is a big difference if the center comb flap does not open like it should. Take a flash light and peek through the grid of the center console when you start the engine. You should see the flap lift.

regards

the flyin' scotsman

mike......I know someone not too far away who could look at it for you......in Edmonton next weekend