Z928328

hello all- I about to bring my car to the AC specialist this week- I already read Wally's print out-

I'm going to replace the expansion valve( Both front & rear), Receiver drier, Green O rings. All these are from Roger.

My AC symptom- It won't hold the Freon for 1-2 days. Shop says it the evaporator in the dash that needed replacement but I'm doing the cheapest option first.

I still don't believe it's the evaporator- because the car has low miles & I assume it's still OK.

So I'm driving the car without AC all the time. But What I notice when driving - There's always air blowing trough the AC center vent- The AC is off. Is that normal?

Please advice.

SQLGuy

That's normal. Air will still blow through as long as the vent is not closed.

Any A/C shop should have a freon leak detector (a little electronic device that senses freon in the air). That should immediately indicate if a leak is coming from the front evaporator.

If it's leaking at the evaporator, that could either be the expansion valve connections (which are outside the passenger compartment, under the splash tray) or from bad/cracked/broken connections in the evaporator itself. If the latter, I would think you'd smell the leak yourself, while driving.

On the other hand, I don't know how the front GTS evaporators were made, but the rear one in my '88 S4 had copper lines pressed into the ends of an aluminum coil, and those connections started leaking after a while. I was able to repair mine with some special solder.

The fact that your shop didn't notice the serious leak in your system before charging (by failure to hold vacuum) or after charging (by "sniffing" for leaks) makes me think you should be checking for alternate shops.

Cheers,
Paul

jmrjames

I am not an expert but after reading about all the time and money you are spending on these guys to experiment with your car seems like a waste.

Go find another shop that knows what they are doing and has the equipment to do it right.

Calgary Ole

I will add to the other response. Here in the northern summers we get temps from 5 to 30 C in a day. In the cool mornings , my auto setting will take a few moments to get to a temp before the fan comes on and warms the car to the temp on the slide setting(say 24 C) Then the heat of the day moves the setting motor to colder until the temp in the cabin is again at 24 C. When its warm I can turn on the AC and the auto setting motor will keep the inside temp to 24 C.
My guess would be your car is blowing air to cool the car to what you have set the temp to be. In your climate without AC it is blowing as cold as the system will allow.

Bill Ball

If it comes to pass that you need the evaporator replaced, be careful with whom you allow to do this. People not familiar with the 928 will probably never figure out how to remove the dash. There are only 4 bolts that hold it on after the center console, steering wheel and pod are removed. If they know where they are, no problem. If they don't, they might end up using a hacksaw.

Z928328

I hope it's the expansion valve & not the evaporator.- I don't like the dash to be open up etc. I will bring it to a different place.

Some facts about the my car-
AC has not been switch on since 1993 & has low miles (1k).
When I sent in for AC recharge- It blows cold air & will lose out freon the next day.

That same week- I sent to the same shop & they just change the "O" rings at the receiver drier fittings & check some hoses."no leaks detected" according to them & they uses some detergent to see if there's leak. They charge the system- & blows very cold air- & lose out freon 2 days. I call them about the problem.

They didn't check the expansion valve or use any dye. but they straight away assume it's the cooling coil/evaporator in the dash.

FredR(rennlist user) from Oman- said it could be also the seals at the compressors due to lack of use & will lose out fast(1-2 days). I was told by the mechanic who install my Timing belt last 2 weeks - to change the whole compressor since denso unit is available easily over here.

I will update again.

jmrjames,

Yea true, but this shop is a expert car AC shop. They did recharge freon on a coral red GTS from the same auction sales with low miles. ( I bought mine from the Auction). His car AC is fine since. I guess he's lucky & another one from the same sales recharge it on the 3rd times with oil- & it's fine since.
https://rennlist.com/forums/928-foru...nd-928gts.html

Calgary Ole,

I usually drive my car on weekend & use it in the evening & night or early morning. Mid day- too hot . Once it has AC- maybe I can use it every time.

.

Bill ball,
yes- I will bring it to a pro & since 928 over here is very rare- I bet most AC shop never seen a 928.

When I did a search on rennlist for evaporator change. I need to see pics of the process( taking off the dash, where the evaporator is located etc)- It seems no one ever change the evaporator? Most failure points is at the expansion valve & the fittings.

Roger sells the new for new USD880 which I think is OK. Dealer over here sells them like 6k.


I will update on the progress.

Z

Nicole

Your car is so new, and there are many potential sources of leaks. The evaporator is probably one of the lesser likely sources of your leak(s).

Fluorescent dye would really help in finding them!

Have you checked the following?

- AC Compressor - where the lines connect and at the front radial seal
- Expansion valves front and rear AC

Z928328

Even the Mechanic that change the Timing belt on my car said it couldn't be th evaporator.

They didn't check the expansion valve & compressor . They jump to their conclusion it's the evaporator.

Z

Nicole

Maybe they are just hungry for a 24 hour job - it's good money for them, after all!

Try to get some dye and a fluorescent light - that will tell the true story very quickly.

Remind us: Does your car have the rear AC? I think it does... more O-Rings, more potential leaks.

Z928328

Yes my car came with rear AC.

The two other GTS from the same sales- have no rear AC & their AC is OK.

Nicole

HA - isn't that something!

Maybe here is a hint on where to take another close look! My first 928 also had a leak at the rear AC - I just don't remember what exactly leaked there.

Asiandude

I recommend you take the car to Ivan at Newera airconditioning, located at the bottom of Jln Telanai on the approach to Bunut. He knows his stuff and is priced competitively. Refer back to my earlier reply; my car has suffered failuire of the HP hose, expansion valve and evaporator (on seperate occasions) it is also low mileage, the heat and humidity out here can cause lots of problems! I changed the evap myself a few months ago (it had started leaking from within the fins and was unrepairable) it's a straightforward job on a 928 IMO,
Best, Joe.

Alan

I think you already reached this conclusion - don't even consider work to replace the evaporator unless it can be proven that this is the source of the leak... not their guess but proof. Not only is is a big expense and time consuming but many other things can get damaged taking the dash apart - especially by somebody who has no idea what they are doing...

I agree the evaporator is one of the least likely leak sources...

Alan.

dprantl

That is ridiculous. Loosing a full A/C charge in 1 - 2 days means the leak is HUGE. You could probably hear it with just your ears when full. It's hard to believe a shop would not be able to pinpoint such a leak within 15 minutes with a leak detector. I was able to hear a leak in mine that lost a full charge in 2 weeks, and that was at the top of the compressor where I couldn't really get my ears to (it was one of the valve cores).

Dan
'91 928GT S/C 475hp/460lb.ft

jmrjames

That is a shame that this shop is considered to have expertise with any kind of AC system. Their method seems to be to add freon and pray. Then keep trying other things until they get it.

Given the fact that the AC system had not been run since 1993 they should have never just charged it and let you go.

They should have done the following:

1) Replaced all of the O rings. Look at their condition from your photo and this statement is evident.

2) Replace the Drier / Receiver. This should be done with each major system work.

3) Replace the Expansion Valves. Also as to why in 2 above.

4) Checked that the compressor was functioning properly and has the proper amount of oil.

5) Replace any hoses that look bad.

6) Vacuum down the system and see if it holds. Meaning No or Minimal Leaks.

7) Place a small charge of freon in the system and then use an electronic detector to sniff out any problems. Much better method than soap bubbles or dye.

8) No leaks found then fully charge the system. Otherwise investigate areas where the detector indicated further problems.

I hope that I may have condensed the advice from the others with this list. If I missed anything then someone should be able to correct my outline.

Best of Luck and hope that the next place knows what they are doing.