Aux fan idea? help me out

[fyrfytr1717]

Good news and bad news...

Good news is that I took a look at the schematic for my Carling switch and found that I can use it to supply a ground signal and have the lights function properly. It's a 5-pin switch so both of the lamps have their own + and - pins. The 5th pin is the incoming signal. The "on" indicator lamp shares a tab with the outgoing signal, but since the lamps are incandescent, it doesn't matter which way the circuit flows. I'll just ground the incoming pin and switch the indicator light's ground to a positive. The lamp will receive it's ground via the outgoing signal.

Bad news is that I have to take down my overhead console and hack into my pretty wiring...

 

[fyrfytr1717]

Wow, took awhile to find the time to get the wiring all straightened out but it works! The Carling switch I'm using has no issues whatsoever with being used to switch ground while still having a functioning indicator light. With the switch in the "off" position, the fan kicks on and off with the A/C compressor clutch as it should. I haven't driven it hard enough to get the fan to kick on due to engine temp, but I'm confident that will work as well. With the switch in the "on" position, the fan kicks on and stays on. The A/C compressor clutch continues to cycle just as it should. The only thing that's a little annoying (but will be easily fixed) is that the indicator light on the switch turns on every time the PCM kicks the fan on. A diode installed in the ground signal wire between the switch and the relay should take care of that. There's no CEL, but I'd still like to hook up an OBDII scanner to make sure it's not throwing any hidden codes.

I'd like to thank MrJCRod for getting me going in the right direction. I knew there had to be a way, but you sure saved me a heck of a lot of time trying to figure it all out!

 

[MrJCRod]

Wow, took awhile to find the time to get the wiring all straightened out but it works! The Carling switch I'm using has no issues whatsoever with being used to switch ground while still having a functioning indicator light. With the switch in the "off" position, the fan kicks on and off with the A/C compressor clutch as it should. I haven't driven it hard enough to get the fan to kick on due to engine temp, but I'm confident that will work as well. With the switch in the "on" position, the fan kicks on and stays on. The A/C compressor clutch continues to cycle just as it should. The only thing that's a little annoying (but will be easily fixed) is that the indicator light on the switch turns on every time the PCM kicks the fan on. A diode installed in the ground signal wire between the switch and the relay should take care of that. There's no CEL, but I'd still like to hook up an OBDII scanner to make sure it's not throwing any hidden codes.

I'd like to thank MrJCRod for getting me going in the right direction. I knew there had to be a way, but you sure saved me a heck of a lot of time trying to figure it all out!

Glad it worked out for you...