I’m board. (Ok, not really; I’m just nearly in over my head here.)

This is the Constant Control Relay Module (CCRM) out of my Mustang. Ford apparently didn’t want me to have access to certain relays, and instead made them part of this module, which runs about a hundred buckaroonies for a remanufactured unit.

That’s right, instead of swapping out a $5 relay, failure of any of the CCRM circuits means a triple-digit repair. Fuel pump relay go bad? Get a new CCRM. Radiator fan relay stop chooching? Fork over the cash. The CCRM also houses the PCM and AC relays, which are all soldered to the circuit board.

My car won’t run right now because I removed the CCRM. And I removed the CCRM because it won’t energize the AC clutch coil (I already performed the other necessary checks and narrowed it down to this module.) I did some research and found that drilling out a couple of rivets would give me access to the circuit board. That’s the easy part. The hard part is, I don’t see an AC relay!

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I identified the pins, traced some circuits, and found the PCM, fuel pump, high-speed fan, and low-speed fan relays. Mind you, the AC was working not long ago, so don’t go thinking that this is a CCRM out of a non-AC-equipped car. The AC circuit just doesn’t use a standard relay; it’s somehow controlled through the other little components.

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There are NO obvious burn marks or breaks in the circuitry anywhere. Everything looks intact. I have no idea how the CCRM’s AC circuit functions, so it looks like I’m gonna have to test each little piece individually. I can check resistors, that’s not a big deal. And my meter has diode and capacitor modes, too. But I don’t know anything about transistors, much less how to test them.

All I’ve managed to do so far is bench-test the relays (all good, as expected) and clean a tiny little bit of green corrosion I found around some of the main connector’s solder joints. (It was around the low-speed fan circuitry, which I believe has nothing to do with AC operation.)

I’m confident that If I put it back in now, the car will run, and keep itself from overheating. But I really want to fix my AC first, and I’d rather not buy a reman unit if I can get this one working instead.

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Any ideas, Oppo?