AC compressor rebuild success

[JayArr]

Hi All

I have successfully rebuilt my AC compressor and thought I'd post up the part numbers for others.

The vehicle is a 2005 Envoy XL with the 4.2 engine.

I did some cross referencing and side checking and took a chance on the Santech shaft seal and gasket set. I wasn't 100% sure but it's in the vehicle working so now I can pass the info along.

Shaft seal MT2158 $17.99
Gasket Set MT2207 $4.59

Purchased both from Autozone, $30.65 with shipping and taxes, a lot cheaper than a rebuilt.

There was nothing wrong with my compressor except that the shaft seal had worn out and the refrigerant had leaked out. You need to disassemble it and your space needs to be clean. After reassembly I added oil to the compressor and reinstalled it with new line seals all around as well. I also replaced the orifice tube and the receiver dryer and added oil to the new receiver dryer. Four cans of 134a went in yesterday (48 ounces) and it's running perfectly, it sits right in zone A of the chart in the service manual and the pressures are all within spec.

I hope this helps someone else avoid spending hundreds for a rebuilt.

JayArr

 

[Mooseman]

That's cool. You didn't happen to see a part number for a new clutch assembly for this compressor? That's where these fail a lot of times.

 

[JayArr]

no, but I wasn't looking. Usually for metal to metal clutches I clean them all up with solvents and then a wire wheel then I sand blast them with garnet to give the surfaces an uneven texture so they grab and hold when they come together. This has worked every time so far for me.

 

[Mooseman]

It's usually the magnet that craps out. The metal clutch wear we can compensate by removing the shim to close the gap. Makes me wonder where rebuilders get theirs?

 

[JayArr]

They're probably winding them in house, you can buy a simple motorized transformer winding machine out of India these days for about 5K. I bought a manual winding machine out of China for less than $100. It works great, just a little slow, we rewind solenoids and transformers all the time with it.

 

[Chickenhawk]

It's usually the magnet that craps out. The metal clutch wear we can compensate by removing the shim to close the gap. Makes me wonder where rebuilders get theirs?

I suspect that is what is wrong with mine. Works good when cool, but stops engaging when hot, especially in stop and go driving. I measured the gap with feeler gauges, expecting it to be huge, but it was within specs. (.025") There is no evidence of slipping and no noises. It just stops engaging. Yesterday, I stopped the fan, reached down with a hammer and gave it a quick rap. It engaged, then disengaged about 20 seconds later. (Engine was running and still hot from driving in traffic.) It just seems to me that the magnet is not engaging strong enough.

I am reluctant to try the shim removal if I am just wasting my time. The gap when cold is not huge.

I can get a new Denso here in Canada for $330 and a new AC Delco for $360. Thoughts?

 

[TJBaker57]

I am reluctant to try the shim removal if I am just wasting my time.

FWIW, Mine had very similar behavior as you mentioned, smacked the clutch and it engaged briefly. Worked OK in cooler weather but failed when hot. I measured the voltage and current draw of the clutch and they both seemed OK. Removed the shim and it has worked fine for years now.

 

[Mooseman]

Sounds like the magnet. You can try the shim. Costs nothing.

I got a UAC from RA for total $275CAD last year for the Saab's 5.3. It's been fine since although I use the Saab infrequently. No ACDelco is available for it. Depends on how long you want to keep the truck. If I was wanting to keep it for a very long time, I might go with the ACDelco or Denso but I think the new aftermarket ones have been improved.

 

[Matt]

I suspect that is what is wrong with mine. Works good when cool, but stops engaging when hot, especially in stop and go driving. I measured the gap with feeler gauges, expecting it to be huge, but it was within specs. (.025") There is no evidence of slipping and no noises. It just stops engaging. Yesterday, I stopped the fan, reached down with a hammer and gave it a quick rap. It engaged, then disengaged about 20 seconds later. (Engine was running and still hot from driving in traffic.) It just seems to me that the magnet is not engaging strong enough.

I am reluctant to try the shim removal if I am just wasting my time. The gap when cold is not huge.

I can get a new Denso here in Canada for $330 and a new AC Delco for $360. Thoughts?

That's the exact behaviour mine had. I just straight swapped it out with a new Four Seasons a few weeks ago...it's nice having functioning AC again.

 

[Mektek]

The clutch in mine was not worn so when I removed the shim I had zero clearance - not good. I made a shim with half the thickness of the original and now it works, but not perfectly. When I rev to 2700+ rpm with a hot engine I can hear the sounds of clutch slip. For normal driving around town it doesn't cause a problem. So I guess I should be thinking of replacing the clutch. I could gamble on a PYP unit for $25............
If your compressor is otherwise working well, probably it makes sense to repair rather than get a rebuilt/used one.

 

[Chickenhawk]

I removed the shim because it is literally only a ten minute job. My clutch plate came off easily, and the shim was about a .020. Gap before was about .025, and after, about .008. (I touched up the plate face with a file to shave down some of the high spots and encourage fuller engagement.) All seems fine, but I will know in the next few days with hot stop-and-go driving. I was worried that my clutch would stay engaged too because my original gap was still within specs and removing the one shim would reduce the gap too much, but I have been engaging and disengaging at idle and at speed and all seems good.

I am speculating that it is not just a larger gap; it is a combination of wider gap through wear, and a weaker coil providing less magnetic pull. But if it gets me through this year, I am happy. Will update my experience more later.

 

[gmcman]

I am speculating that it is not just a larger gap; it is a combination of wider gap through wear, and a weaker coil providing less magnetic pull. But if it gets me through this year, I am happy. Will update my experience more later.

I also removed my shim when the A/C was cutting out on occasion, that was about 3-4 years ago and still working.

 

[TJBaker57]

speculating that it is not just a larger gap; it is a combination of wider gap through wear, and a weaker coil providing less magnetic pull

Anyone ever suspect that these rubber(?) grommets that compress when the clutch is activated are not as supple as they were when new? Mine are original, made in 2001. I have a notion that they are part of the issue.