I'm trying to run all the gremlin's out after my head gasket fix. I'm down to my last one. My AC will not cut the compressor on - the light comes on in the dash (which really doesn't mean anything). Things I know - the fuses behind the glove box are good, I did not discharge/unhook or mess with the AC unit in any way other than the belt, when it should engage (ac on, fan blowing, engine running) the wire that engages the electric clutch only reads 0 volts.

I'm at a loss here - any help would be appreciated.

 

The FSM says there is a ground point on the left side of the radiator...anyone know where that is? I don't see it.

 

any chance you don't have the dual-pressure switch plugged in?

edit- that's under the dash so probably not the problem.

 

I'm looking for that guy...where is it?

 

left side of the radiator, when in the driver's seat.

 

http://www.ncttora.com/fsm/1990-1995...c/componen.pdf
go to page 5 and look for the circle with A13 in it, near the top right of the image, and follow the line down

 

I'm still drawing a blank. I did not unhook anything behind the glove box - nor does anything look out of place. All the fuses there are good.

Can anyone think of something under the hood that would cause these symptoms if not plugged back in?

 

I'm drawing a blank as well. Maybe there's a plug that's not seated properly.
Have you tried triggering the a/c clutch with a jumper from the batt?

 

Yep...kicked right in.

 

--Coolant Temp Sensor - may have an input, on EFI if the engine is overheating, the ECU will not allow the A/C to come on, if it doesn't see the Coolant Temp Sensor it will not turn A/C on at all (may have 1 sensor for the gauge & 1 for the ECU)

also check to see if the A/C relay is clicking or turning on, if it is turning on follow the wire up from the compressor and look for stretched/broken wire (may have pulled on something and caused the problem), give a light tug on the wire going into the connector (if it comes out, that was your problem)

 

well... umm... Given that, did the a/c start blowing cold?
If not, I think you need to put a manifold on the A/C system and check the lo and hi side pressures. For some reason, the A/C amplifier is not triggering the compressor.
But if it did blow cold, it may be a plug disconnected or not seated properly also.

 

I did not find any sensors loose or unplugged. I suppose I'll have to check their wiring next. I think there may be validity with the ECU temp sensor theory.

 

*&#@^%$!!!! Its a leak! I must have dinged the condenser. I suppose I'll have to get a can of that UV dye to be sure. That really sucks.

<end_rant\>