To check for a bad gound, the easiest way is to use an ohmmeter. Push probe to a well grounded location and use the other probe on any ground wire that you wish to test. Anything more than 1 ohm should be cleaned and retightened.
It might not be a ground circuit connection but a faulty Power Control Module or a leaking vacmun line.
The A/C compressor relay is activated by the PCM and if it is kicking n and out, the PCM is either faulty or it is getting the wrong signal from somewhere.
The heater fan should not turn the compressor on unless it is shorted to the circuit.
Here is a wiring schematic. Note the location of the ground circuits that should be checked.
Friday, August 20th, 2010 AT 7:26 AM