98' S-10 Air Conditioning problem?
 

My AC is acting up. I've owned this truck for 3 years now. The former owner installed a new compressor right before I bought it. I checked the low pressure side fitting and I'm fully charged with freon. I checked the fuses and relays and they are good. What would cause the compressor to NOT engage "sometimes"??? Today it's working great:crazy: The engine is the 4.3

Re: 98' S-10 Air Conditioning problem?
 

I forgot to add, I've noticed the problem only on really humid days. Is there a sensor that detects humidity that would cycle the compressor on and off???

Re: 98' S-10 Air Conditioning problem?
 

The high side pressue would make it do that too. (To much head pressure) I don't think there is a sensor that senses humidity.

Re: 98' S-10 Air Conditioning problem?
 

My 96 does the same thing, but only if I dont use it all the time. Mine has something to do with the wiring plug on the pressure cut off switch on the accumulator. If I unplug it & plug it back in, it will sometimes go. If not I jump the leads & it will take off. Hows that for backyard repair? :lol:

Re: 98' S-10 Air Conditioning problem?
 

Was a new high pressure switch installed on the new compressor? If jumper the compressor at the low pressure switch, you can determine which switch is not kicking on the compressor.

Re: 98' S-10 Air Conditioning problem?
 

I have no idea if a new switch was installed. How do I jump the switch and where is it located? Thanks

Re: 98' S-10 Air Conditioning problem?
 

Re: 98' S-10 Air Conditioning problem?
 

Andy, by jumping, do you mean bypass the switch somehow??? Do I run 2 leads to my battery from the accumalator?? If so does it matter on + and -? Thanks

Re: 98' S-10 Air Conditioning problem?
 

Pretty sure you just need a paper clip or jumper wire between the two connector wires.

Re: 98' S-10 Air Conditioning problem?
 

Thanks corn! So far it's been working fine but maybe the switch is going to go up this summer. No biggie, it should be easy enough to fix.

Re: 98' S-10 Air Conditioning problem?
 

Sometimes the clutches start to go on these compressors. Gently tap it and see if it kicks in.

Re: 98' S-10 Air Conditioning problem?
 

FYI, a system with a 10% charge will have correct pressures at rest. but once activated it will run down the low side fast and kick off. since the refrigerant carries the oil to the compressor a low charge will destroy the comp., fill the condensor with debris, coat the inside of lines and evaporator with "black death" reducing system efficiency, and plug the orifice tube screen.

make sure the system is full with the correct charge by weight, NOT PRESSURE

Re: 98' S-10 Air Conditioning problem?
 

Re: 98' S-10 Air Conditioning problem?
 

UPDATE- the AC has continued to work intermittantly for the last month even though it "mostly" works. Yesterday I noticed when I stomp on the gas pedal to downshift the transmission it will kick ON the compressor and then the AC works fine. I always thought the WOT sensor or TPS is supposed to shut OFF the compressor when you downshift. Basically it's acting the opposite of the way it's supposed to:uhmk:. So now I'm thinking a sensor on the the throttle body needs cleaning or replacing. Am I on the right track???

Re: 98' S-10 Air Conditioning problem?
 

the ECM turns off the compressor during WOT by deactivating the clutch relay. if the TPS was acting backwards you would be asking about severe driveability issues instead. after re-reading your posts i am wondering if the ECM is recieving a constant request from the control panel (bad switch on dash). it sure wouldn't be the first time I seen a bad HVAC control panel on a late model GM.

of course as luck would have it I am now home for the weekend and not at work. if someone (CORN) could remind me on Monday I can check to see which wire sends the AC request signal to the ECM. then I could post that and you can check for an intermittent open. hint-hint larry