I have a 1993/94 940, non-turbo. Love the car but the AC quit. It appears the clutch is not engaging. Don't know if AC is on, or off with dash button out?

Is there a way to test the AC clutch? Any other ideas on where to begin trouble shooting are appreciated

 

my 92, the button is labeled AC OFF, and pushing it IN disables the AC, leaving it OUT turns the AC on.

but, its not 'always on', it cycles according to the temperature setting. the control signal goes from the dashboard A/C control module to the pressurestat on the side of the reciever/dryer, to another pressurestat on the condensor manifold, and thence to the compressor. if either of those pressurestats is 'open circuit' then no AC. one pressurestat tells it there's not enough pressure in the refrigerant, and the other says there's too much pressure.

I'd unplug the pressurestat on the reciever/dryer, and measure the voltage at the two pins on the harness plug... one pin should be 12V (give or take) when the engine is running and the AC is switched on. if you don't see 12V there, then odds are fairly good the dashboard controller is dead. Also measure the resistance between the two pins on the pressurestat itself, it should be 0 ohms, if its open circuit, then odds are there's no freon in the system, or the pressurestat is bad.