Air Conditioner electrical question

[nborton]

I lost my air conditioning recently I had replaced everything in the system last year, so I don't suspect anything mechanical.

When I switch to a/c inside the cab, I hear the vacuum system moving, but the compressor does not turn on. I tried checking voltage at the connector and had some odd readings of 300dc volts, so something must not be connected right.

Can someone point me in the right direction? I looked at the wire diagram and believe connector 138 is the one at the compressor, where is 137 relay control or 109 a/c wiring harness? maybe it came disconnected when I was reconnecting my vacuum line last week.

Thanks all

BTW: I picked up my grandfathers 97 Buick Skylark to be a better commuter. With only 32,000 what could go wrong? I'm going into week 2 and have already replaced the drivers window motor, battery, and alternator. Of course Oil, plugs, wires, air filter, fuel filter were just for fun. The tensioner pully on the transverse mounted motors is darn right impossible to get to with a ratchet, so I used a 6 foot concrete break bar and wedged it in there and used the sheet metal under the hood as a pivot =)

Bottom Line, it's not a syty thing, it's a GM thing.

 

[myclone]

Re: Air Conditioner electrical question

I lost my air conditioning recently I had replaced everything in the system last year, so I don't suspect anything mechanical.

Was it cooling fine then just quit or did you notice that the AC was slowly getting less cold over a period of time. If it was ice cold one day then the next day it was dead Id suspect an electrical issue. If it slowly lost its cooling capacity Id say you have a leak that eventually caused the system to lose enough of its charge to actuate the low pressure switch which cuts power to the compressor clutch (the connector you were using a volt meter on).

Quck test is to unhook the connector on the low pressure switch (on the dryer) and jumper it out with a piece of wire. With the engine idling and the switch jumpered (HVAC controls inside cab set to MAX AC) the ac system should almost immediately start cooling down. If it doesnt after a minute or two the system has a leak and the refrigerant has escaped. If on the other hand it does cool down then you have an electrical issue (usually the low press switch you jumpered is bad in my experience).

BTW, when you say you measured 300v were you using a digital meter? If so was it in auto ranging mode or set for ~200v scale? If so I bet you were seeing 300 millivolts not 300 volts (unless you were testing plug wires while the engine was running ).

 

[nborton]

Re: Air Conditioner electrical question

Wow that was quick, I haven't even finished reading other posts =) It was ice cold and then hot. I'll try and jumper the dryer, and yeah my digital voltmeter is a pcoket craftsman and it probably was mv, but it's too small for me to read the little extras..

 

[nborton]

Re: Air Conditioner electrical question

Thanks, jumped the connector and the compressor ran fine, although I could hear it wasn't moving anything through it. So, I'll close the electrical thread and look for the leak =( Every peice of the system was new a year ago. It was ice cold a few weeks ago and now. Maybe it had something to do with the 13 110+ days we had. I'll bower some gauges next week and see what psi I have in the system, if it's fine, than I'll be back..

 

[EcSy#2671]

Re: Air Conditioner electrical question

your pressure on the low side should 40-45 psi at idle. Hope that helps you later.