Anyone have the wiring diagrams for making your own E-fan harness? I have one, but thinking of making one for the PCM to control. What are the relays for? I figure one is for the A/C on, but what are the other two? Thanks

 

I had to make one for my a/c...using the pcmforless harness. I merely used a relay to change a pos to a neg and used the manual switch wire from bryan's harness to one side of the relay and the dark green wire from the a/c to the other side. Works flawlessly. As for the other two...I have no real idea.

Pat

 

Just a guess here...but I think one is switched on when the PCM triggers, one is switched on when the a/c triggers, and one is switched on when both other relays are switched on.

 

the relays are allowing you to use a lower power control signal to power something that requires much more power and not have to run long lengths of wire that is moving lots of current, where you get into resistance, heat, not so good performance, etc...

i drew up a simple diagram when i installed my fans using 3 relays. 1 relay each for the fans and another relay using the A/C compressor signal to run a single fan. it was a high-speed only, both fans would run when reaching the temp setpoint. if the A/C was on a single fan would run unless it reached the temp setpoint and then the other fan would start. when the temp fell below the setpoint and the A/C was still on only 1 fan would shutdown, and of course both would shutdown if the A/C compressor wasn't energized.

 

Thats helpful. I know what a relay is for, but I'm sure some people dont. I didn't think of that though. I guess I'll draw something up tomorow at work. Thanks

 

I did these when I put mine in:
2-relay

3-relay

the pictures are kinda big, you might want to print them out.