RIP AC compressor?
 

Hi guys, I was hoping someone will know what I'm dealing with re: an inop AC system. I originally assumed I could give it a charge and be back on top, so I bought the DIY hose with gauge and a couple cans of R134a. However, the low side pressure was over 100 psi even with the engine running and AC on full blast. I looked down at the compressor and noticed it hadn't engaged.

I figured I'd check to see if it was lack of signal (therefore probably a bad sensor) or if the compressor itself was dead. So, I jumpered 12v from the battery to the pin on the compressor. It switched right on! I checked the vents in the car, and I was getting cold AC! So, then I checked the low side pressure and it was around 40psi, pretty much right on given the 85 degree temps.

However, around that time I noticed that there was some noise coming from the front of the engine, presumably from the compressor. I revved the engine a little, and it stumbled badly returning to idle. I did it again (for some reason) and it stumbled quite badly, then made a loud buzzing sort of sound (almost an electronic sounding beep) and stalled. I immediately disconnected the power lead to the compressor. It (the inner part of the clutch) then slowly spun a few rotations, with the engine off. I think it spun opposite from normal.

What does this seem to indicate to you? I'm thinking it doesn't bode well for the compressor's continuing to work, but the thing that puzzles me is why I would have both a compressor on the brink of death, and an apparent signal problem. The system was not being powered on... I know it can turn the compressor off if the outside temp gauge or the pressure sensor in the compressor are not working properly, but I don't think it would be able to detect if there was some other issue with the compressor.

And, what can actually go wrong with a compressor? The seals must be OK as it was compressing. The bearings seemed to spin fine at least at first. I can spin the inner part by hand, and it feels smooth. And the clutch seemed to work. I don't know what to do next here. Any help appreciated!

Mine did the same thing. The high side is leaking into the low side. I am in the process of replacing the compressor and hoping it fixes it. My parents Kia minivan is also doing the same thing. the seals are okay, but its an internal leak. it lowers back down to 40ish when you jump it since it just compresses it to the high side.

thats the best i can tell you, hopefully someone will be able to help you better.

Thanks for the reply. You don't think there's any chance that's normal operation- for the pressure differential to equalize when the compressor is off?