I have a 97 Sable wagon as a second car since i'm dropping in a new motor for my other car. The Texas summer is really starting to kick my butt and my A/C is not working at all. I admit i'm not really into these cars, I bought this as a temporary vehicle till I get my main car running again.

I figured that it was low on freon so I hooked up my manifold and saw the low side pressure was perfect. I turned on the car and set the A/C to max and watched the A/C clutch refuse to engage.

Turned the car off and turned the compressor a few times with a crowbar, its not frozen. I can hear the blend door move into position, but since I don't have a factory manual or even a haynes manual I can't trace the wiring. The only fuse under the dash that I figured was related to the AC was not blown. None of the fuses are bad sans the ciggerette lighter fuse.

1. System has plenty of freon.
2. Compressor is not frozen.
3. Blend door works

I wish I had a diagram... Anyone have any advice?

 

refrigerant pressure sensor may be bad. However, changing it means evacuating the system and recharging it. There may also just be a wiring harness disconnected. If you set up a login on autozone.com you can get access to wiring diagrams (if they have them) for your vehicle. I'm not so sure about vehicles made after 1996, but I know most if not all vehicles have the diagrams for before that. Check it out. Hopefully it's something simple.

 

Don't forget about the box of relays and maxi fuses under the hood.

 

Autozone has nothing on the diagrams. I guess I'm going through each relay one at a time. The compressor mag switch is hooked up. I don't know were the pressure switch is located.

 

the pressure switch is usually on or near the dryer/accumulator. Not real sure about your specific car though.

 

I have a 96 Sable wagon my wife drives and it has similar A/C problems. Cultch kicks in and right out again. The fuses are okay and has good freon pressure on the low side. Are the relays under the hood interchangeable? Is there an available trouble-tree or wiring diagram someone could steer me to?

 

did the gauge show good pressure with the compressor running or with the system idle? The reading should be taken with the engine running and air conditioner running. if the gauge bottoms out when the compressor kicks on, then you don't have enough refrigerant in the system. A co-worker's car had that issue. with the system off and everything off, the system showed 40psi. When the compressor kicked in, the gauge droped to 0psi almost instantly. took almost a whole can of r134a to fill it up (tiny system on a geo metro though. my MGM takes 2 cans to fill).

 

The clutch won't stay engaged long enough for a change in pressure. Had 70 psi on low side without compressor running.

 

when the a/c clutch cycles on, the pressure should change instantly.

 

if the pressure isn't changing, then there may be something wrong with the compressor. If the clutch is engaged for half a second, you should see a change in pressure. If the clutch is not engaging for even that long, there are definitely other issues.