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Discussion Starter · #1 ·
1995 Mustang GT, 177,000 miles

I'm taking a chance, posting this in the 5.0 section. It's really more of a SN95 concern in general, but it looks like CCRMs are engine-specific, so here goes...

Well, it finally happened. After seeing so many other SN95 owners reporting CCRM failures, I poked around with my meter and narrowed down my recent AC inop issue to the CCRM. (Thanks, Ford, for putting these relays in a "non-serviceable" box...)

I've seen some write-ups on how to avoid buying an entire module by soldering relays on the CCRM. Now I may be a noob at electronics, but soldering a relay like that is totally something that I can handle.

So I removed and opened up my CCRM and took some time to identify the pins and follow the board traces. I found the fuel pump relay, the PCM relay, and the low- and high- speed fan relays. Unfortunately, there's no AC relay in here, like there is in later cars. The AC must be somehow controlled by the other little components on the board (resistors, diodes, etc.), and I'm afraid I'm at a loss on how to proceed here.

I did find a little bit of green corrosion between some solder joints that seemed to maybe be barely bridging them. Those joints are for pins 2(Cooling Fan Motor LOW Output), 3(BATT + Cooling Fan Control Relay's), and 14(Low Fan Control Input). The corrosion was also getting kind of close to the joint for pin 13(Ignition hot in start or run).

I cleaned up the corrosion (but not before taking these pics). I don't see any other visual problems, and I plan to put a fresh layer of conformal coating on the board before re-installation. I also manually tested each of the four relays just for kicks, and sure enough they're still working great.

Could that corrosion have been it? Is there anything else I should do before re-coating the board and putting everything back together? There's no AC relay, but is there a way to bench-test the board's AC clutch circuit first?
 

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Discussion Starter · #3 ·
Remanufactured ones. Kinda pricey compared to a $5 relay, though.

Before I opened this up, I was looking at pictures of how to do CCRM repairs, but those pics must have been from newer cars, as those boards have an actual relay in the corner. This one seems to use a bunch of resistors, diodes, etc. to energize the AC clutch, so it's not as simple as swapping out a relay after all.

I'd really like to get this module working again if I could. As it stands right now, all I've done is clean up a little bit of corrosion, and I'm not confident that it was the problem. My AC issue was intermittent, so there's a good chance that simply plugging this back into the car will be inconclusive. I need to be able to drive it around to verify, but that's going to have to wait until the conformal coating I ordered comes in. So in the meantime, I figured I'd post it here and see what you guys think.
 

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I forgot to update this thread!

So I started checking components one at a time, but I got stuck when it came to the MOSFET. Despite the numbers printed on it, I couldn't find any specs (not even a data sheet) to determine what kind of readings it was supposed to be giving out. And on top of that, I couldn't match up a new one even if it was bad. That was the dealbreaker for me, and I stopped checking other components.

So I gave in and ordered up a remanufactured CCRM. It worked, and it fixed my AC problem, but before completing the installation, I opened it up to have a look inside.



This is a newer design, which probably came out of a Taurus or something, judging by the Ford number printed on the board. The MOSFET is gone, along with a lot of other components, replaced by a more normal coil-type relay.



On the back side of the board, it's kind of ugly. Solder everywhere, but it doesn't appear to be bridging any circuits that shouldn't be bridged. My guess is, this is to reinforce the traces.

There were a few dry spots without conformal coating. Some was rubbed away from the edge of the board, and some appeared to have burned off during the remanufacturer's repairs. Fortunately, I had bought some in anticipation of fixing my original board, so I used it here. It looks a lot better now, and I feel better about putting it in my engine bay, too.

 
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