PCM and A/C request interface OBS wiring

[RedHeartbeat]

Has anyone here wired in the A/C request signal into the LSx PCM with an older vehicle? I have a Sanden compresser that only uses a power lead to trigger the clutch. When I turn the A/C on the engine wants to and usually does die unless I two-foot the pedals. Its even worse with the transmission in gear. HPTuners has an idle control to raise the engine RPM and adjust for the additional torque load with the A/C request but how to I send a signal to the PCM from my 93 dash control to let it know the A/C is on?

[GMCwantsLS1]

I just ran the wire that went to the old pressure switch(the one that comes from the switch on the controls) to the PCM AC request.

[RedHeartbeat]

Do you remember which lead on the PCM? I tried Red 17 to no avail.

[GMCwantsLS1]

C2 red pin 17. This was on the 02 Camaro PCM I used in the 81 truck. It is kind of a complex system. The PCM senses actual pressure on the high side to know when to turn on the cooling fans. The compressor is variable displacement so it doesn't cycle on and off like most do. It still should work to make the idle compensate for the AC. I think it also senses the compressor is on with another wire to the PCM. Pin 18 red is AC compressor supply voltage. I think that means it senses when the compressor clutch is actavated.

[1BadAction]

I just ran the wire that went to the old pressure switch(the one that comes from the switch on the controls) to the PCM AC request.

in other words, the OBS electronic controls already produce a positive A/C request signal? so the only thing that needs to be done, is hook the dark green A/C request wire to the correct LS1 PCM pin(C2 17) instead of the original PCM? Thanks.

[GMCwantsLS1]

in other words, the OBS electronic controls already produce a positive A/C request signal? so the only thing that needs to be done, is hook the dark green A/C request wire to the correct LS1 PCM pin(C2 17) instead of the original PCM? Thanks.

Correct.

[r6z4o6]

http://www.ls1truck.com/forums/lsx-t...estions-2.html

Check out the attached thumbnail on post #13.