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93 940 No AC, no power to compressor EDIT Correction-Update 900 1993

"An idea as to which relay I would be looking for on the panel or will that be self evident when I see it?"

When you say "which relay", I'm thinking you're looking at the main relay rack behind the fuse panel. But that's not where the AC clutch relay is. It lives alone on the AC control module PC board (in the FAQ pictures I posted yesterday).

I believe the FAQ has instructions on removing the AC module for access to the PC board. I've never done it myself, but before you dig into it, I'd advise you to use your 12V test light* to check for power coming (from the relay) to the Cycling Switch on the receiver-dryer where you were earlier.

I guess you already "jumped" that Low Side switch earlier, but did you have the Key On, AC button activated, and blower fan running? Those 3 things [actually 4 things] are needed to activate the MCC (Manual Climate Control) unit. If you do that set-up and see voltage at one of the two switch wires, then the relay is providing it. If not, then you will need to get the control module out.

EDIT: Actually those "3 things" above aren't quite enough. The engine must also be running. I just tried it on my car where I have a "telltale" light (see pic below) to indicate compressor clutch operation. I used the fan switch to complete the circuit and it took about 2 seconds for the light to come on.



* Glad you're using a test light vs a DMM. I think there are many cases on these older cars where a "trickle" of voltage will look good on a digital meter, but not push enough current to power a relay etc. The test light will give a more valid indication of adequate voltage,
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.






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New 93 940 No AC, no power to compressor
posted by  leylandauto  on Tue Jul 20 02:51 CST 2010 >


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