EFIDynoTuning Forum

Trying to figure out how to make my MS3 run the stock AC system.


But Im honestly not sure where to start on this, guess knowing the proper function of the whole circuit would help.


Looking over the PCM pinouts you have it seems that theres 3 pins that go through the PCM for the AC system


#41 AC HP
#69 AC wot switch
#86 HVAC



I would wager that #41 and #69 are grounding signals sent to relays in the CCRM to cut power to the AC clutch field.


What does pin #86 do?

41 is the cycling switch input. 86 is head pressure input. 69 is WOT cut out relay. PCM will not "run" your ac. It will cut the compressor clutch for excessive pressure, or WOT.

Just hit it with 12v's



Make doubly sure pressure is in spec.



Cccool