Diagnostic Notes. [Diagnostics] Where can I hook up a jumper wire to see if the AC compressor clutch is still good?
[Herb Goltz] In 740 cars, remove the connector at the low pressure switch on the accumulator/dryer (the aluminum cylinder at the firewall). Jumper across the two terminals inside the connector (a paperclip works fine). With the AC set to on and the engine running, the compressor should engage IF the terminal inside the connector is receiving +12V power via the 10-second delay relay behind the glove box. In 940 cars, remove the same low-pressure switch connector at the receiver-dryer and jumper it: current comes directly from terminal 10 of the MCC control unit with no relay. [Larry Spooner] If there is a circuit problem after the above test and you want to test the compressor directly, unplug the connector in the black wire going into the clutch assy. If you have an ohm meter there should be a low resistance 3-5 ohms measured at the compressor side of the connector to the compressor body or engine block. You should be able to jumper this directly to the pos battery terminal or the B+ t
