SteveZ Z-28

All,

I have a 1994 Chevy Camaro Z-28. It had been sitting for a while (lot of repairs and other things got in the way), basically for 3 years. I've gotten it back up and running finally. Now the A/C doesn't work... It did work when it was running 3 years ago. I put my manifold gauges on it and I am reading about 130 PSI on the high side and the low side is off the gauge (high) completely. The compressor is not coming on.

Keep in mind that it is about 100F outside when I took these readings.

A couple of questions...

Is it possible that some of the freon bled over from the high to low side while it was sitting?
Would the compressor not come on if the low side is too high?
Would it be possible to somehow get the compressor to run (jumper it) and hopefully the low side would correct itself? Could this hurt the compressor/system if I did this? How else could I lower the low side to an acceptable value?

I've read that it could be a bad compressor or expansion valve... I'm hoping that it isn't either of these and that the system just needs to be recharged.

Thanks!

parkers Z28

try to disconnect the positive side of the battery cable this will reset the pcm

SteveZ Z-28

That has pretty much already been done... While the car was sitting dormant, the battery was drained. I had to take the battery out of the car to recharge it.

bobdec

After sitting for 5-10 minuets the high and low side should read the exact same pressure as the system equalizes when the compressor is not running. At 90* F air temp the R-134 pressure on a static system (compressor not running) will be about 90-95 LBS so your system at 100* F looks OK with 130 lbs of pressure. You do not need a charge.. Most manifold sets go at least to 150 lbs on the low gauge, swap the hoses, put the blue one on the high side of the manifold set and use the high gauge to verify low pressure NOTE do not do this w/compressor on.. they have to be equal when static...if not let us know! As far as jumping the compressor , pull the AC relay and jump panel pins B1 to B4 it will throw a small spark and the ac clutch should engage. You can do this with ignition on and engine off and just listen for a solid click of the clutch engaging. W/engine running it should start the compressor. REMEMBER this test will throw a DTC code (clutch voltage present w/o PCM commanding AC relay pick) that will prevent normal AC operation and the PCM must be reset to allow normal operation. Here is a schematic to follow if clutch does not click ref shbox.com http://shbox.com/1/hvac_compressor_control.jpg . If clutch picks, start engine and see if compressor runs with jumper, if not clutch is bad (slipping/burnt/ect) if compressor runs then it's either bad relay, circuit from PCM to relay,or a solid error DTC in PCM preventing relay pick.. You will then have to get it scanned.. Good luck , keep us updated..