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fred4man April 15th, 2011 10:14

A/C Compressor Troubleshooting and Recommended Replacement Manufacturer
My A/C stopped cooling in my ’02 Jetta wagon 1.9 TDI so I investigated and found the following –
  • Did the radiator fan check per instructions on the forum – fans working OK
  • When turning the A/C on and off at the pushbutton switch, the motor does not load up, the HP-LP gauges do not indicate a change in pressure, and the compressor clutch operates as it should (and the compressor rotates).
  • So it appears to me the compressor is not compressing. The obvious is to change the compressor, air dryer, and o-rings, Then vacuum down the system and recharge it.
Questions –
1. Am I missing something else which could be causing the problem or is the compressor the “smoking gun”.

2. Which brand of compressor is considered best? I have seen Sanden (which is the brand in there now @ $400), Behr ( listed @ $300), and Denso ( listed @ $400). Isn’t Denso the brand used by Toyota?

3. Anyone tried rebuilding a compressor?

4. Any other A/C parts which should be changed out or checked while doing this work?

Thanks for your help!

jkaiser April 15th, 2011 11:34

if you turn the compressor by hand is there much resistance? You are sure the clutch is engaging properly and the compressor is spinning? I had to replace the magnet/coil last year in mine. Same symptoms but no clutch engagement. Sounds like you are on the right track.

Vertexboy April 15th, 2011 11:56

A/C trouble
Did you say the clutch is engaging and spinning. The clutch is the part the magnet pull onto the pulley. When the two are locked together the system generates pressure. So if the clutch is spinning but not enough pressure is being generated the refridgerant level could be low (caused by a leak). I would recommend having professional use recovery machine and weigh how much refridgerant is in the system. Good luck

fred4man April 15th, 2011 12:14


I thought you had a great ides. I had pulled the skid plate last night. So I went ahead today and more closely checked the rotation. Unfortunately the clutch is engaging.

With egine off I could, with some resistace, rotate the compressor by pushing on the lugs which protrude from the end of the pulley. SWAG at 3-5 ft-lbs resistance, felt like seal friction. Don't know how much resistance I should expect at hand-turing rotation speed? The pumps are variable displacement so I don't know if this affects the torque at low speed?


The pressures were high on the gauges. So I don't think the r-134a is low.

Thanks, guys for the comments.

Any one have comments on relative merrits of the compressors available?

josh8loop April 16th, 2011 09:15


I rebuilt my Sanden SD7V16 compressor recently(about 10 mths ago) on my 2002 Jetta TDI. It turned out to be a bad control valve. While I was in the compressor, I replaced all the seals, and o rings. Check out this thread:

I got all my stuff from Polar Bear, and they were great to deal with. I ended up replacing my evaporator, expansion valve, orifice tube, all internal compressor seals, dryer, and all the O rings I could physically get to in the system. If you PM me, I can email some photos of the compressor internals for you. It was a tedious process, and I think I had around $100.00 tied up in the compressor parts alone. It was however rewarding to do something myself that most people don't atempt. Good luck!

josh8loop May 10th, 2011 15:46


How did your A/C repair turnout?

fred4man May 13th, 2011 15:21


Ordered control valve and gasket kit from Polar Bear in FL - all for under $60. They have a "tech documents" section for customers where I downloaded a manual for the SD7V16 compressor.
Had a shop recover the 134a.
Pulled compressor and rebuilt it. That was not difficult as per your instructions. I noticed that compressor looked very clean inside, no signs of wear, so I was optimistic. Also noted that when they recovered the 134 they pulled most of the oil along with it. (There was no large accumulaton in the compressor and the dryer. There was oil in the 134 when I had prevoiusly disconnected the hoses doing the pressure checks. I guess that happens when the system is recovered propely?)
Bought O-rings, expansion vlv, and dryer from IDParts - They sent wrong o-rings so bought correct ones from local stealer.
Installed Oil in compressor. PAG #46 from NAPA
Installed new components
Borrowed friends vaccum pump and system was tight! So far so good.
When charging the pressure would only go up to 75 psi on high and 35 psi on low and still did not load down the engine when I turned AC on and off and never got cold.
Prior to rebulid the pressure only changed 5 psi (I lost the notes)

SO I broke down Monday and ordered a new compressor from Pelican (I buy a lot of parts for my wife's BMW from them). I guess I screwed up the rebulid.

josh8loop May 13th, 2011 16:16


I was hoping for a smashing success story-sounds like it turned out to be a bit more than just a control valve then. I guess you will know once you install your new compressor. When I rebuilt mine I was thinking that even if my rebuild didn't work I would only be out a small amount of money-fortunately mine worked out. Maybe yours needed a new valve plate to- hard telling. Let us know how it goes on your new compressor, and keep in mind you might be able to sell your control valve and other compressor parts. Good luck

lmathies May 17th, 2011 18:42

Hi, I have a 2001 Jetta TDI. My AC suddenly stopped blowing cold air. THe fan still blows air, just not cold. When I turn the AC off, I hear a chattering noise under the hood. WHen I turn it on, the noise stops but the air does not blow cold. Any suggestions?

josh8loop May 18th, 2011 03:37


Originally Posted by lmathies (Post 3407655)
Hi, I have a 2001 Jetta TDI. My AC suddenly stopped blowing cold air. THe fan still blows air, just not cold. When I turn the AC off, I hear a chattering noise under the hood. WHen I turn it on, the noise stops but the air does not blow cold. Any suggestions?

You may want to post a fresh Thread so it will get more attention. I am still thinking about this topic, and hope to come up with some solutions soon.

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