Anybody know if the signal to start the A/C compressor is a positive or negative Signal? And which of the two wires sends the signal? Can't seem to locate my shop manual (recent move) and I'm hooking up the A/C to start my electric fans when it kicks on, would just test the connections but both batteries are out of the truck at the moment.

 

It's 12v.

My 2004 shop manual wire colors won't match. However, I'm willing to bet that one of the wires coming out of your clutch is black. Do a continuity check on the black one to ground.

I assume you are going to use the 12v wire to fire a relay for the fans?

 

Gee I kinda figured it was 12v....I wanted to know if I was looking for a positive signal (like when the accessories I attached come on, or is it a negative(ground) signal(Like when the headlights come on). And yes I'm using it to fire a relay for the fans, but the wire has to connect to one of two different connections on the fan depending on the output signal.

 

Do it this way and you won't be back feeding to sensor circuit and computer relay outputs. I would use a double pole relay and switch common(gnd,) as well. If you can not figure out which are pos and com mabey you should not try this
Clark


no
12v+ batt------o
relay contacts ====o==to fan
12+ exist to fan------o
nc
O--------to 12v+ ac
O coil
O--------to 12v- ac

 

Forgot to line up
no
12v+ batt-------------o
relay contacts ====o==to fan
12+ exist to fan------o
nc
O--------to 12v+ ac
O coil
O--------to 12v- ac

 

Use a diode across the relay coil to clamp the spike from the relay coil or at least to one in series with the coil to compressor ckt.
I use them to protect the electronics and to steer the circuit.
Just what I do.
Jim