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Another VW problem - compressor?

fasto on Tue October 02, 2007 4:15 PM User is offline

Year: 1993
Make: VW
Model: Corrado
Engine Size: 2.8
Refrigerant Type: R134a
Ambient Temp: 70
Pressure Low: 35/75
Pressure High: 140/75
Country of Origin: United States

Hi, I wish I had found this forum a few weeks ago!

The compressor in my VW (SD7V16-1102) was stuck on maximum displacement - I thought. High side pressures were outta sight. Finally the compressor clutch bearing started making noise with the AC off. I decided to fix it once and for all.

Car notes: I have had this car since new, and it's always been R134a. The AC has always been lousy. The dealer "fixed" it within a few weeks after I bought it and I think that's how I got a non-original condenser (see below). All 3 radiator fans run on all their speeds. Airflow through the condenser seems OK. Airflow through the evap seems OK, but I plan to pull the fan and shop-vac the evap again. The car has a cabin air filter which I change every couple years.

System notes: the car takes either 800 +/- 50g or 850 +/- 50g depending on if you look in the service manual or on the hood decal. There is no low temp switch on the evap. There is a low ambient temp switch in the fresh air intake duct, set to 32F. There is a low R134a switch, set for 15PSI. There is a high R134a switch, set for 350(!) PSI. All the electrics seem to be working correctly.

System flow: Comp -> condenser -> rcvr/drier -> long hose -> sight glass -> HP valve -> TXV -> evap -> TXV -> muffler hose ->comp

I installed:
New TXV (old one was leaking)
New rcvr/drier
"rebuilt" compressor (I think I blew it here).
I flushed all lines except for the muffer line.
I flushed the evaporator.
I flushed the condensor. The condensor on the car is not original much to my surprise. It's a tube & fin design, probably courtesy of the dealer repair in 1994.
There was nothing of note in the AC system. No metal, no black glop, just bright green PAG oil. I took the old compressor apart and all the reeds are OK. The nose seal is leaking, though, probably why the clutch bearing failed.
I drained the oil from the "rebuilt" compressor.
Reassembled with new o-rings. Pull vacuum for 30 min, leak test for 1 hour. No leaks. Broke vacuum, added 100cc of Castrol PAG46 with dye to compressor,
15cc of same oil in the TXV end of the muffler line, revacuumed and leak tested again, OK. Turned compressor about 100 revolutions by hand.

Begin filling with R134a. After about 100g of referigerant, turned on AC to help with filling. Compressor ran OK for a few minutes then the clutch dropped out. Voltage was still getting to the clutch.
Eventually I discovered the clutch air gap was about 4 times to large and couldn't be adjusted any smaller. I exchanged the clutch disk with the old compressor, and set the air gap correctly. I also discovered that the "rebuilt" compressor that I got was an SD7V16-1100 with an -1102 pulley on it (the part number & serial number have been sanded off the compressor sticker). I also discovered the compressor crankshaft has about 0.100 inches of end play; it can be moved in & out of the housing about 0.100 inches.

Now, the clutch stays engaged. I managed to add R134a up to about 750g. The compressor pulls down to 30PSIG low side and builds to 140PSIG high side. This is not great but at least it's compressing. After five minutes or so, something happens and the low side & high side pressures equalize at the static pressure (within 5 or 6 seconds), about 75PSIG on the day I checked it. The clutch is still engaged and I can see the compressor crankshaft rotating. The sight glass appears to show some flow, though this could be residual I suppose. This condition continues until I switch off the AC and wait 30 or so minutes. Then, I can repeat the cycle.

What's going on here? I can only think that the TXV valve is stuck wide open or the compressor has an internal leak.

Oh, the compressor "rebuilder" won't take the (wrong) compressor back. He says that if I send it to him he'll "rebuild" it again for me. Of course, the car can't be driven without the compressor, and it's about a 6 hour job to r&r the compressor to boot.

Any thoughts? Sorry about writing a novel here! If I can add any more info I'd be happy to.

Chick on Tue October 02, 2007 4:52 PM User is offlineView users profile

You have a bad compressor, with a sticking refrigerant control valve, check out the compressors on the sponsors site for a "Quality" compressor. As far as how much it takes, always go by the underhood sticker..Hope this helps...

Email: Chick


Freedoms just another word for nothing left to lose

mk378 on Tue October 02, 2007 8:40 PM User is offline

There's no way the clutch can stay adjusted with that much end play in the shaft. You really should insist on your money back, don't trust another one of that guy's rebuilds. The next one might go to smithereens and contaminate your system.

badufay on Tue October 02, 2007 9:19 PM User is offline

I am finishing up a battle with a reman compressor myself right now. Luckily I was able to return mine and upgrade for a new one. Lesson learned for both of us (and for anyone else for that matter)...Never buy a reman compressor!!!! If you end up biting the bullet and buying a new one, buy one from these guys. Besides the fact that supports this forum, you won't find a cheaper price on new VW compressors. Trust me I have been looking for them for some time. I bought my reman from autozone, before I found these guys. VW's are not happy with reman compressors. My vent temps increased by about 15 degrees F (does anyone know how to type the little degree circle?). Anyway, good luck in getting your VW fixed. I have dumped more money into trying to re-troubleshoot it than i would have if i would have just bought a new one from the get go!!!!


TRB on Tue October 02, 2007 10:03 PM User is offlineView users profile

Just a heads up, I did get your email and doublee checking the condenser for you. New Sanden is my suggestion on the compressor.


When considering your next auto A/C purchase, please consider the site that supports you:

fasto on Wed October 03, 2007 5:23 PM User is offline

Thanks all, I appreciate your help. I do now realize that I got a "spraycan rebuild" compressor, and I have asked the ackits guys for some quotes for new parts. The original "rebuilder" won't take the "rebuilt" compressor back because "it's been installed on a car", so it looks like I will have to go to the credit card co. to get satisfaction.


badufay on Wed October 03, 2007 5:46 PM User is offline

That sucks...I just put the brand new compressor in my VW, and everything works great!!! The pressures are much more stable, and the vent temps sit at about 40 F when the outside temp is 90 F. Go new, it will save you the headache later on.


Edited: Wed October 03, 2007 at 5:50 PM by badufay

TRB on Thu October 04, 2007 10:40 AM User is offlineView users profile

Ok sorry for the delay. I believe Rob provided you with a quote yesterday. If not I suggest a new Sanden compressor drier, exp device and condenser. Which I finally got an updated image from our vendor. This looks to be similar to the one you sent me. But the one you sent was not the best for comparison.


When considering your next auto A/C purchase, please consider the site that supports you:

Dougflas on Thu October 04, 2007 12:27 PM User is offline

Is this what you're trying to type? 32º Fairly easy. On the PC, hold "alt" key and use the number keypad 1 6 7

fasto on Thu October 04, 2007 5:52 PM User is offline

Yep, that's the condenser I need, email sent.
Thanks, Aaron

fasto on Mon October 08, 2007 4:49 PM User is offline

Order Placed.
Thanks, Aaron

TRB on Mon October 08, 2007 4:59 PM User is offlineView users profile

I see that, thank you for the support!


When considering your next auto A/C purchase, please consider the site that supports you:

fasto on Wed May 21, 2008 12:06 PM User is offline

I wanted to update this now that it's what passes for spring in New England. Last weekend I completed this installation.

The compressor (Sanden SD7V16-1102) gets an "A". The right part, only one tricky thing in that the adjustable sleeved nuts on the end opposite the pulley need to be adjusted which I didn't realize at first.

The condenser, well, it's about the correct one. I'm not upset with ACKits, or even the manufacturer; I have a car that had a total worldwide production of about 8,000 units that hasn't been made in 15 years so demand for the car-specific parts has to about zero. I find that almost all aftermarket parts fit quite poorly and require considerable rework.

For the condenser, the condensing part was almost correct but the mounting brackets are totally wrong. They are correctly shaped but the proportions are wrong. It looks like the manufacturer made them from a non-dimensioned picture. I made a new set of brackets. I had to bend the condensor inlet and outlet pipes quite a bit to match up with the hard lines on the car and I was concerned with the Aluminum condenser cracking, but it did not. After installation I had to bend it some more to get the inlet connector away from the radiator, and I still have to do more bending because one of the aluminum hard lines on the car is still rubbing the radiator support.
Anyway, after a considerable amount of cutting, bending, drilling, sawing and tigging I had the condenser mounted.

I drained the oil from the compressor, and added a bit of PAG46, turned the compressor, then drained again. I didn't flush the system as the service manual notes how much oil is supposed to be in each part, which I added back to the compressor, receiver/drier, and condenser. I was changing the compressor because of a faulty RCV and the condenser because of bad condition of the fins.

I reconnected all the lines, new O-rings, nylog on the O-rings of course. Pulled a nice vacuum which held properly.

The amount of refrigerant on this car is in some dispute; I found values ranging from 800+/-50g (service manual), 850+/- 50g (underhood sticker), 900+/-50g (Alldata), 1000+/-50g (a TSB) so I decided to treat it like an unknown. I charged 2.1 pounds as liquid into the high-side port as I believed that about 0.1 pounds would be left in the manifold & charging lines, this should give me 900g in the system.

Started it up, AC on MAX, high blower, doors open, ambient temp about 70 degF. @1500 RPM, Low side 32 High side 140, evap inlet cold evap outlet quite warm. Undercharged, I believe. I added refrigerant as gas in small amounts until the inlet & outlet of the evap were about the same cold temperature.
After a bit of adding and rechecking, I ended up with about 975-980g of refrigerant in the system.
Ambient temp 65F (but underhood temp was >110F), @1500 RPM, Low side 32 High side 220, vent temp 42F. Seems OK so far.
Of course it's been in the low 40's high 50's since then so I haven't been able to check at high ambient temps yet. We're supposed to have 72-75F this weekend and I will recheck then. (Spring in New England, eh? It feels like a late October day today!)

Overall I am happy with the results. The trouble with the poor fitting condenser is a problem with having an old obsolete limited production car and is something that I should have expected. The service from ACKits has been topnotch. When I have some more run time on this system I will update again
Thanks, Aaron

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