Hello,

I have a 66 mustang and I had a cowl issue which I fixed by pulling the heater box out and putting a cowl hat in. But when I went to put the heater box back in and later went to use the heat I realized the heater motor wasn't coming on.

My buddy looked at it with me and we figured out if we pulled the wire off the heater motor and hooked it to ground on the battery the motor came on. So I ended up clipping the wire on the heater motor and running it to the chassis ground.

That's all good, now I have heat. Problem is now the motor won't go off. I did a bunch of research to understand how the motor resistor works and the switch works so I was going to try and test the switch.

Now even when I pull the 3 way switch connector off the front of the heater box for the heater control. The heater motor is still on.

Is is possible what I thought was ground is not ground on the motor? Or does ground vary (that sounds wrong to even say)? Could the resistor on the heater motor be stuck on? Something else?

Any advice is much appreciated. Thanks in advance.

 

The heater blower connects to two female bullet connectors typically located on the wiring bundle clipped to the passenger side export brace above the heater blower. Neither of the two wires of the heater blower are grounded.

If your wiring harness is intact this should do it for you.