Automotive Air Conditioning Information Forum

1987 Chevy R30 truck. H6 compressor was brand new about 18 months ago. Entire system had been replaced with new components back then - evap, condenser, accumulator, compressor and all lines. Used 8oz of PAG46. System worked great until last winter. Discovered a leak between the case halves on the H6. Finally got around to getting a replacement compressor while it was still under warranty.

Pulled off old compressor and went to drain it to see how much oil to add back in. No oil came out of compressor. Noticed discharge port was black and sooty. Pulled accumulator to see how much oil was in there. None.

Pulled orifice tube. First thought was "I thought I put in a blue, not a black". It was black. Not wet and chunky black like black death, but dry and sooty. I wiped some off and snapped a picture -



I was ready to put in a new compressor, orifice tube and accumulator, and add back in however much oil came out, but now I'm not sure how much oil to add or if the system needs a complete flush to remove whatever this black stuff is. Again, there are no signs of metal or anything else, and the black stuff is totally dry like soot.

Question 1 - where is my oil?

Question 2 - what is this black stuff?

Question 3 - do I need to do a full flush of the system?

Thanks

Did the compressor seize when you began having trouble with it?

99 Caddilac Deville Base, 67K miles, with 18 oz R134a (Calls for 32 oz) blowing pop off valve on compressor when 18 oz gets in system. Temp 95, low side 35, hi side 100, engine 900 RPM. Pulled Orifice tube, appears to be in backwards. The long part was toward evaporator, and it was covered with BLACK SOOT ! No metal filings. Looks like a rebuilt compressor, not OEM, has orange tag saying 9366 on it. What causes this black soot? What is the correct orientation of the orifice tube?

Did you accidentally post to the wrong thread? This one began with an '87 Chevy truck and you're talking about a '99 Cadillac DeVille. I'm confused.

As for the orifice tube, the long screened part should point toward the condenser, not the evaporator.

JohnHere wrote:Did the compressor seize when you began having trouble with it?

No. It just quit blowing cold. There were signs of oil around the body of the compressor and on my valve cover. Compressor still spun freely when I turned it over by hand.

87 views and no one has any idea what the soot looking stuff is or any ideas where my oil went?

1) Out of the belly leak on your compressor.


2) Powdered compressor from running without oil


3) If that much of the compressor wound up at the OT, yes I would clean everything & replace the condenser.

Sorry you didn't receive an immediate reply. I've been thinking on this for a little while.

I believe bohica nailed it, though. I can't say for sure 'exactly' where the oil went, but it does sound as though the compressor ran completely dry and ground itself into oblivion. The material from the compressor destroying itself internally, sometimes appearing like ground black pepper, is what you found clogging the OT.

As bohica said, clean (flush) the system well before reassembling with the appropriate new parts. Excellent advice.

Thanks guys. I replaced the OT and the accumulator. I did flush out the evap and the condenser and didn't really get anything out of them. Refilled with oil and vac'd it out and charged it up and things are working nicely again.