The AC Compressor runs all the time when the engine is running on my 88 Caravan. The clutch will not disengage. The heating and AC switches are all turned off. If I unplug the clutch it disengages ok. What will cause this?
Go to fig.12 and enlarge it and look at the A/C compressor/blower motor circuit here: http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?pageId=0900c1528021617b
Follow the Dk Bu/Bk wire up to the A/C compressor clutch relay. If unplugging this relay turns off the compressor, then maybe the PCM is keeping the relay coil grounded through the Dk Bu/Or wire all the time?
The Dk Gn wire from the A/C blower motor relay supplies (+) power to the A/C compressor clutch relay turn-on coil. Does the blower turn all the way off when the control panel switch is turned fully off?
Has any wiring modifications been done or did this problem just start?
Some quick relay, meter or test light probe checks should give an answer or at least a diagnostic direction.