Whistler

iTrader: (46)

The car is an LS swapped Chevelle, and we added a vintage air Gen IV AC unit, which works great when the vehicle is moving, but has no interface with the cooling fans. So the AC can't be run when idling because of lack of airflow and high head pressure.

The car is running an OEM harness and PCM, with the 3 fan relays in the OEM fuse box. Those relays are triggered by grounds from the PCM, while the AC compressor control is 12v+

I'm drawn between adding a seconday relay circuit for the AC control of the fan, or wiring the command for the AC compressor through the PCM, which I'm not sure how to do. Any input?

rao

iTrader: (18)

The wiring is fairly straight forward

https://ls1tech.com/forums/conversions-swaps/841036-ac-pressure-sensor-question.html

You didn't mention what year PCM you are using, so be sure to check the pin outs for your application.

Whistler

iTrader: (46)

It's a 99

oange ss

iTrader: (50)

could use the PCM to control an A/C fan relay or use the A/C clutch signal wire to control a relay for the fan...

ImStock

X2 thats what i was going to say.

rao

iTrader: (18)

That's about 10x easier especially if you don't want the PCM to otherwise control the compressor.

Whistler

iTrader: (46)

The fans are factory LS1 fans from the F body that the engine came from, and are controlled by the series of three relays hooked to the PCM. I don't want to remove the low speed/high speed functions that they currently have, and hooking up a separate relay circuit will probably mean just that .

oange ss

iTrader: (50)

you can still wire the clutch signal wire to any of the relays that use a pos voltage to activate, just use a diode so the signal doesnt back feed..., the problem with signal control instead of pcm is the fan will run when ever the A/C is on instead of using vehicle speed to disable the function...