[mattdavis11]

I'm posting here b/c it's not specific on the application. What I need to do is add an auxiliary condenser fan to a truck, my concern is how to wire it.

I'm working on a 06 Dodge 5.9 Cummins, which has an inherent problem with the electrical fan clutch. This truck has been hopped up, so who knows why it won't work properly. Restoring to factory is not an option.

What I'd like to do is wire in a pusher fan that is activated when the compressor is engaged. I need a schematic. The best I can gather is that a relay energized by the compressor coil wire can be wired in so I can run the fan directly off the batteries. I'm not an electrician when it comes to wiring in extras, but I can only guess that I need a 4 post relay?

How would you wire something of this nature? I'd rather not wire in a dash mounted switch as this requires competence to turn the fan on when not moving down the road.

The reason I want to do this is because the high side pressures spike when the factory clutch doesn't want to behave. The OE compressor locked up, and it's the fan clutch's fault, and it's a huge problem with these vehicles. Right now I'm testing the quality of my parts and my work, and have told the owner to turn the system off when under 30mph. That's not acceptable, but I can't find a good answer either. The folks on the Dodge boards repeatedly call the condenser the evaporator, so I can't feel very comfortable with any solution that might be offered there.

How would you wire it?