NEPA11

Hello all,

Hopefully someone can help. I currently at a roadblock in my 66 rebuild. I recently started putting the heater system back together. I purchased a new heater box, heater motor, and resistor. When I turn the car to the on position the heater motor runs regardless if the heater switch is in the on position or not. The only way to kill it is if I unplug the black wire from the motor in the engine bay. I know the wires and fuse box are good because I just replaced the whole thing. Is my heater switch wire bad? Would the ignition switch be causing the issue? It seems like it should only get power when I move the heater switch to the right for fan speed but it’s on all the time.

Any help is greatly appreciated!

Thank you!

NEPA11

I guess let me ask this, if I unplug the three wire plug and bottom yellow plug on the resister, should the fan shut off? It does not currently.

fastbackford351

Grab your 12v test light, start at the switch and start chasing sparks. A factory wiring diagram would be helpful but is not necessary. It has been a while since I have messed with it but from the back of your on/off switch, the feed should be hot with the key on but the load side should not until you turn the heater switch on. I'd start by disconnecting the load side of the switch and see if that kills the fan. If it does then it would seem that your switch is shorted out. If it does not turn off when you disconnect the switch then you have an external feed coming in somewhere it shouldn't. As long as your harness isn't hacked & whacked all to pieces these old wiring setups are pretty straight forward.