| Important things learned about A6 AC compressors [message #92551] |
Mon, 19 July 2010 09:06 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Times like this, you just can't help learning things and some of them could be valuable both to your own situation and may help others.
On the way to a fireworks show July 2nd, the clutch had squealed then locked up hard enough to snap the belt (that was good actually). I know the structure of the nose of an A6 real well, and was relatively certain that the surfaces that the clutch bearing fits would be damaged. I did not want to deal with that. It turned out that the important surfaces were undamaged, but the bearing had done some collateral damage to the snap ring and groove.
My compressor has been noisy and long as I have had it. I got the coach with the cab AC dead and repaired it, and convert/recharged it with 134. I had drained the lube from the compressor and was sure to put oil back in the system as I went along. That may have been part of the noise problem.
This was when I had hoped to put in a non-A6 replacement and change to HC12a. Time for Plan B.
Since I was now going to have to put an A6 back on the engine, I elected to find a new part (as I had heard of a number of failures of rebuilt units). Nobody had a listing as they only sell by application and 1975 Olds seems to have fallen off the books(expletive deleted).
As I was dealing with a clean system again (in preparation for the new pump), I had to find out what was the right oil for it. Surprise, last time I had used the wrong oil and about half of the required amount. References seem to vary a little, but the A6 requires 10~11oz. of PAG 150 oil and the system will harbor another couple. The canned oil charge I had used nearly four years ago was about half that of PAG of undetermined viscosity. I re-drained the compressor (not too difficult on a bench), so I was able to pour 10oz into the compressor and fabricate a blinder plate for the ports - so it didn't lose it while juggling the pump back to the mounts. I would have replaced the dryer if I had also converted to HC-12a, but as the system had not been open, I did not. It did dismount it and pour a vary small amount of the old lube oil out of it and then put about 2oz of new PAG 150 back in before I put it back in. That makes at total oil charge of 12oz. of PAG 150.... The compressor is now much quieter than it has been.
The replacement game was dead for now. So, pull the clutch and look at the bearing. It takes a special puller, I called a number of local parts/service shops to see if anybody had the puller. One said he did and it turned out the the kid on the telephone is mechanically challenged. So I went on to an Autozone - none are close, but this one is often on my way to other places. It took three tries to find that their tool 27002 fits old GM A6. We pulled the clutch off and I looked in at the bearing - Oh Dear.
I took it home to my own tools to go on from there. Getting the snap ring out was a challenge, but it came away and the bearing came out oh the sheave with only the expected effort. The outer lip of the snap ring groove had been damaged and had to be filed before the new bearing to go on.
The same AZ had a bearing in the store later that afternoon.
I now have an working system with much less noisy compressor.
Summary:
An A6 needs 10oz of oil plus the amount that will not get back to the compressor (about 2~3oz in a GMC)
That oil should be 150cts (PAG for R-134a).
AutoZone tool 27002 will pull the clutch off the shaft.
AutoZone part number for the bearing is 1960.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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