[Supras] A/C oil loss: don't waste money like I did

[berniek at technicaldevelop.com]

Bob and list:

    I had the same problem with mysterious R-12 loss.  I had no leaks of R12 which were detecable, including sniffing at the drain hose for the evaporator casing.  So I dutifully brought up the R-12 charge each year or two.  In 2002 (car is a '90) the compressor started to seize.  So I bought a new one at Advance (was under a different name then), new clutch because the old one would not fit, new belt because it was slightly different in length than the old one, and got it all toghther, after swapping the hose connection cover on the compressor.  Also replaced the filter-dryer of course.  Put in 6-7 ounces of oil.  Pulled the system down and charged with R-12 (good stock on hand).  After spending almost $600 I had AC again.

    Later I took apart the old compressor and found the swash plate follower shoes had slightly scored the aluminun swash plate.  Teflon piston rings were fine.  The reed valves do not care about oil.  It appeared that If I had added perhaps 6-8 ounces of oil and nothing else, everything would have been OK.  Further, I cut open the old filter dryer, and found a few metallic shards on the outside of the filter element which looked like they were there from parts fabrication when the car was new.  NOTHING MORE WAS FOUND.  That was also a comforting observation to make sure that nothing of consequence got into the expansion valve.  So if you lose oil, let the system down, remove the hose plate or suction hose, and add 6-8 ounces of oil in the suction port.  You may save yourself a lot of money.

    I also found that you can check the oil in the compressor sump by letting the system down, removing the hose plate and bending a piece of 1/16" wire to get past the swash plate the the bottom of the compressor housing.  Insert the wire in the suction port, and wiggle it to get past the swash plate.  The wire acts as a dipstick.  About 1-1/2 to maybe 2" of oil depth is right.  Do it quickly, though, and get the system back together fast, then pull a deep vacuum immediately and recharge.  

    Hope this helps others on the list to save $600.

                BernieK