82 Gen 1 Coyote Swap AC Questions...

[thinkfaster]

I've got an 82 with a Gen 1 coyote swap that I'm installing a brand new LMR coyote swap AC kit on. Previous owner cut back and taped up wiring for all of the the "unused" OEM plugs in the engine bay.......including the ac clutch & pressure switch wiring. I've since found all of the wiring have been doing some basic system testing, but CANNOT get the AC relay under the steering column to successfully energize without physically moving the contactor or momentarily touching 12v to one of the two black/yellow wires running from the AC relay to the compressor clutch. The relay will then stay engaged and shuts off when pressure switch circuit is opened or when AC is switched off on the dash controls as it should.

I found this diagram posted by @Mustang5L5 on another thread and it got me curious: Do the pre 87 cars have a diode in the AC clutch harness?

Here is what I believe to be the original 82 Mustang/Capri wire diagram for this circuit - I do not see any mention of OR diode symbol in this circuit:

Plugs noted on diagram in circuit:

 

[thinkfaster]

Pretty sure I got this sorted last night after a few 12oz cans of thinking fluid. Ended up adding my own 12v signal wire to energize the relay, added a 20A 1000V flyback diode in line on the power wire from the relay to the compressor clutch, and grounded the other wire on the compressor clutch. AC clutch engages when AC is selected on the dash controls and disengages when I remove the temporary jumper wire from the pressure switch. In the future, I plan to use a ZEX 82108 adjustable TPS switch (or similar) to incorporate an AC clutch disable feature at ~75%-80% throttle, which was a solution I found on a corral.net thread.

I also got a 4 pack of "towed vehicle diodes" on amazon for $25, basically a 2 input/1 output diode (similar to the one offered by PBH), and tapped into the constant 12v wire on the pressure switch to trigger the constant duty fan solenoid when AC is running. solenoid was just wired direct to the fan trigger blunt lead on the PBH body harness and controlled by the coyote ECM before. Here's a screenshot of the fan wiring setup: