Engine fan wiring problem

[Jimmyhoffa816]

Truck is 1998 Freightliner classic Peterbilt style removable sleeper. Engine 2000 525 N14 Cummins.

Trying to figure out how to wire my engine fan to kick on automatically when needed. Right now only the switch in the truck will control it. It's not a factory solenoid. It was on here when got the truck but I want it to kick on and off if needed like when idling over night etc. Pictured is the setup right now I have the dash switch wire directly connected to one of the wires coming off the solenoid on one side of the rabbit ear sensor in top off rocker box, The other wire is connected to the AC clutch. Any help on how this should be wired for it to work with switch and automatically would be greatly appreciated because when I idle over night I have to leave fan on fearing if it overheated. And also since I have to leave in it runs way to cold when it's 0 outside.

 

[Hammer166]

That's a one-wire solenoid, right? You want the A/C & temp sides in parallel. So you'll have a hot from the high pressure switch on the A/C (only with the pressure high,) running from there to the output side of the temp switch. And then a hot to the other side of the temp switch. That way if either circuit closes, the fan will come on.

Pulling the A/C side from the A/C clutch is a bad idea, as that will cycle the fan clutch every time the A/C clutch kicks in. I don't remember when Freightliner started putting the fancy A/C controllers on trucks, but I'm thinking that may be old enough it will just have a normal high-pressure switch.

 

[Jimmyhoffa816]

The fan solenoid has two wires. The AC clutch has one wire only

 

[Hammer166]

If it has two wires, most likely the switches ground the circuit.

And not the ac clutch, there's a pressure switch up by the drier