I've got a 96 K1500 Suburban. The a/c compressor compressor (clutch) is now on always when the engine is running. The a/c switch light on the dash toggles normally, but has no effect. The compressor clutch releases just fine when the wires to it are disconnected. The a/c relay is not shorted and works fine. It seems the relay coil is always energized by the ECM. This is where I lose it. Is there some way to diagnose it through the ECM? Do I need to replace the ECM? Where is the ECM? I have a Chilton manual with wiring diagrams, but I can't see how the a/c switch on the dash feeds into the ECM. Any help is greatly appreciated.
-Roy