An A/C clutch is just an electromagnet, There 2 wires on the plug, power in and a ground. Applying 12 volts the the positive side of the coil will electrify the magnetic field and that grabs the steel disc on the clutch and forces it to rotate with the motor.
Doing this is a valid test, but be aware if there are any issues with the system that the safety features are keeping the clutch from engaging and you manually engage it the system pressure may go through the roof and explode with great force. Make sure your static gas pressures are good (both high and low) and you have no pinched lines anywhere.
If you put 12 volt to the coil and the clutch does not engage then the coil needs to be replaced.
Rich
Friday, August 16th, 2019 AT 6:27 PM