A/C will not disengage

[tonytaylor85]

Wrecked 2000 GT 5M. Bought bone stock, running, flawless 2001 GT automatic.
Swapped engine, trans, engine harness, instrument cluster, and PCM from the 2000 GT 5 speed.
The rest of the car is a 2001 GT automatic. No problems with A/C before the swap. Didn't break any lines or lose any refrigerant during swap.

With the 01 auto CCRM, the A/C clutch comes on with the key, regardless of HVAC switch position. I even pulled the cycle switch and the high pressure switch, and it stayed energized.

With the 00 5M CCRM, the clutch comes on with the key OFF, and releases with the key on. Again, HVAC controls had no effect, and I don't recall if i pulled the switches.

Does anyone have any experience with the A/C clutch not disengaging? My wiring diagram from EBSCO shows that the circuits, wire colors, and pin connections are all the same. However, it also shows that power to the coil goes through those switches i pulled the connectors off of. Something seriously fishy going on here.

 

[wmburns]

Do you have the wiring diagrams for the 2000 and 2001 model year? I mean the FULL Ford wiring diagrams?

I asks because there are very slight differences in the model years. Pay particular attention to the AC pilot duty circuit in the 2000 compared to the 2001. Careful reading of the diagram also shows difference in how the CCRM works with the AC safeties. The change was made between the 2000 and 2001 MY.

There is a note in the 2001 Service manual stating there was a change in design of the AC controls. Basically the 2001 PCM has full control of the AC clutch. This was done to allow the PCM to run the AC clutch for a few seconds after start up during some cold periods to prevent slugging of the AC compressor.

This is different in how the 2000 works. The safeties are hard wired into the pilot duty circuit and work without any help from the PCM.

So what you have is a body harness that matches 2001 but the PCM is expecting the logic of a 2000.


There is also a note on the 2001 CCRM stating "REVISED".

This may be something as simple as the clutch logic was reversed (IE voltage start vs ground start). I don't know how to fix as this would require a very detailed comparision of the wiring diagrams. Beyond the call of duty to do "just for fun".

If interested in getting the accurate Ford wiring diagrams, I maybe able to help. PM.

 

[tonytaylor85]

That is very much what i suspected. The wiring diagrams i have are helpful, but not 100% "detailed" we will call it.