I used an old refrigerator compressor for years, it finally laid down and I found a wet vane Robinaire pump for $100 in like new condition. I felt that it was a bargain. The refrigerator compressor would pull about 25 or 26 inches, good enough. There is a write up at www.aircondition.com about how to make a fancy pump out of one.
I would not flush the compressor, simply pour out all the oil you can get out of it. Additionally if you are going to use PAG, you really need to flush EVERYTHING. It is not as compatible with residual mineral oil as is Ester. If you will flush all lines, the condensor, the evaporator and replace the filter drier, PAG should work good, especially with your R4 compressor.
If you really want to be thorough and do a good job, get the brass conversion fittings rather than the aluminum ones from AutoZone. Also replace all the o-rings with the r134 compatible ones and use the Nylog lubricant on them.
I don't know exactly which kits you're talking about. If you're talking about the one with the single hose and some r134, these are called "death kits" at aircondition.com. This does not mean death of the operator, but death to the air conditioner. If you are talking about the retrofit kits with Ester oil, fittings and a few o-rings they are okay. They, however, usually have the aluminum adapter fittings rather than the good ones. The brass fittings are available from acsource.com for about $3 each.
Also, Carrameow, be careful with the manifold on the back of the R4 compressor. Loosen the bracket on the line that clamps it at the upper part of the compressor mounting. Get the lines loose, so that you can start the center manifold bolt in straight. Once you have it in place and tight, THEN tighten the line brackets in place.
Once everything is flushed make sure you get the correct amount of oil in place and pump it down well. r134 is more susceptible to combining with moisture to make acid than is r12.
Last edited by LarryBible; 07-23-2002 at 02:05 PM.