AC functions controlled by the PCM?

Covers most all 98 fords including mustang v6, v8, cobra, lincoln town car, grand marquis and crown vic.
redtopracer
Posts: 97
Joined: 2021 Mar 24, 10:32
Location: springdale arkansas
Vehicle Information: 98 mustang gt 5 spd

AC functions controlled by the PCM?

Unread post by redtopracer »

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?
Schemasservice
Posts: 30
Joined: 2022 Apr 18, 23:00
Location: Faribault, MN
Vehicle Information: 68 Mustang with 96 Explorer 5.0H.O. Stroked to 347. Trickflow intake/ heads. Flowtech custom Cam. CTBAE, SLL4.

Re: AC functions controlled by the PCM?

Unread post by Schemasservice »

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.
redtopracer
Posts: 97
Joined: 2021 Mar 24, 10:32
Location: springdale arkansas
Vehicle Information: 98 mustang gt 5 spd

Re: AC functions controlled by the PCM?

Unread post by redtopracer »

Just hit it with 12v's



Make doubly sure pressure is in spec.



Cccool
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