98 A/C Problems

Having a problem with my A/C .... The switch lights up and indicates that it is running, but the compressor does not engage. I spent two hours troubleshooting the electrical. Seems everything is fine, except the the ECM doesn't trigger the A/C relay switch to close the circuit. If you replace the relay with a jumper wire, the compressor engages normally. Is there a sensor somewhere that tells the ECM not to turn on the compressor? I'm pretty mechanically inclined, but I have no experience with A/C systems. Any help or ideas would be much appreciated.

There is a sensor that cuts off the compressor when you floor the accelerator. Maybe thats stuck closed.

Any idea what it's called, and where to find it? Can't seem to find a mention of it in the Hayne's manual, nor at Alldata.com either. Thanx for helping.

could be a bad ac dash switch.

If it's low on refridgerant it won't come on.

Abuddy at work said the same thing about the refridgerant - I am going to get that checked today or tomorrow.

you said if you replace the relay with a wire it works fine? that says to me that you need to replace the relay

I checked the relay, and it functions fine - I then replaced it with a known good unit, but it still didn't work. The pressure thing sounds logical to me; as for the switch, electrically it seems to have the correct readings and resistance when checked with an ohmeter. Thanx. Hopefully I get this figured out soon - it's starting to get warm........

adding coolant is easy, just buy an A/C kit they are about 30 bucks at walmart and it comes with the hose and all the refigerant and oil you will need. hook it to the low side port start the vehicle turn on the A/C and puncture the can. Its a pretty easy project

if you have the 4 cyl model there is a good chance your P/S pressure switch could be the cause of your concern

adding coolant is easy, just buy an A/C kit they are about 30 bucks at walmart and it comes with the hose and all the refigerant and oil you will need. hook it to the low side port start the vehicle turn on the A/C and puncture the can. Its a pretty easy project


One can of coolant did it - I never realized it was that easy. Thanx again, everyone.