1993 RWD 2.3

AC is on even though the switch on the climate control is turned off. Where should I start my troubleshooting?

 

First the obvious, AC is on when AC switch is on, of course, OR when DEFROST is selected, if slider is left on Defrost then AC won't go off


Start with the fuse, pull out fuse 17 in cab fuse box, that should cut the 12v thats being sent thru cab control switch to WOT relay in engine bay fuse box, this is to see if there is 12v short somewhere so AC clutch is getting 12volts from another system

The 12v power path is like this:
Cab fuse 17-----------climate control---------------------AC pressure switch(es)----------------WOT relay----------------------------AC compressor clutch

WOT relay is a 5 pin relay, when its OFF it pass the 12v to clutch, when its on it cuts the 12v, then computer cuts the 12v when driver presses gas pedal to the floor(Wide Open Throttle, WOT) this is to give driver more power to pass or ???
If you pull this relay AC clutch should get the 12v

Unplug pressure switch and see if one wire has 12v, key on/AC on, then turn off AC and see if 12v is gone, if not then AC switch in the climate control is bad, stuck on

1994 and 1993 AC are the same

 

Unplugged the fuse. Wasn't blown and the AC clutch turned off. Plugged it back in, clutch turned back on.
Unplugged the connector to the AC pressure switch, AC clutch turned off. Test with voltmeter and there was 12v with both the climate control turn off and on.
Plugged the connector back into the pressure switch, AC clutch no longer turns on regardless of climate control.

Assume that the climate control is bad. Thoughts?

 

Yes, reads like the AC switch is damaged, shorted, so always passing 12volts to AC system