kikcaffine

Hello,
I have a few questions pertaining to the a/c system on my 91 s13. I have an SR in it, but have a KA compressor swapped onto it, utilizing all the factory components. About 3 weeks ago it worked fine, but I way way way over charged the system and blew the over pressure valve out of the bottom of the compressor. Bought a new used compressor that was supposedly good, but not real way to tell, and put that on the car. Added the 8oz of PAG oil like the compressor said it required and went about charging the system. The compressor will cycle on and off for a second but not actually compress or make the air cold. I can bypass the safety switch and it kicks the compressor over, but doesnt actually blow cold. The low pressure sides reading right at 40psi, but the high side is 100. Some times though, if you flip the compressor off and then back on it will bounce up to about 200psi, blow ice cold, then cut back out. The system was vacuumed for about 30-40 minutes and help a perfect vacuum at that point. I was doing some reading and it seems maybe the expansion valve could have died? Or is there something else I should be looking towards?

omgosh

First off the whole system takes 8 oz of oil. So you probably over oiled it at least 4oz depending what was in the old compressor.

What youre describing sounds like the variable displacement part of the pump is getting stuck. You could try unsticking it by running the engine at ~2500rpm and turning it on and off 20-30 times.

However if its not staying on and is properly charged you have a problem with the pressure switch or ac circuit somewhere.

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kikcaffine

Would the variable displacement portion be the reason it comes on and off for a second? The compressor's clutch is constantly engaged, it just doesnt seems like its actually compressing anything. The pressure switch has been by-passed also.

omgosh

I had a compressor that was stuck in the minimum-stroke position once. It would kick on and blow cold for a couple seconds but then you could feel the load come off the compressor (idle would rise to about 1100) and it would stop cooling. It sounds alot like that so thats why I mentioned it.

It could also be way under charged.

Also I would think you can just change the burst disc or whatever the over pressure release thing is in your old compressor. The point of it is to release pressure before anything is damaged or explodes.

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kikcaffine

Yeah Im thinking Im going to put the old compressor back on with the new burst disk. After the first can of R134 the ac was ice cold, soon as we added the second 12oz can, it got hot. I appreciate your help omgosh!