Can a heater fan relay short out?

[lyonsronnie1]

Folks, the heater in my old Valiant hasn't worked in a few years. Specifically, if you hook up the heater relay, the fuse blows. The relay is on top of the heater box.

If you run a jumper wire under the hood to the heater fan, it turns on and works fine.

I've used an ohmeter on the relay, but I don't know what kind of resistance I should be getting across it. It looks like it's just a coil of wire, is that right?

I'm thinking maybe I've got something else going on somewhere else, though that gets connected together if I plug in the heater relay.... if I leave it unplugged, the fuse doesn't blow.

any suggestions on how to systematically figure this sucker out? Or do I just likely have a bad relay?

66 Valiant, btw.

 

[67Dart273]

There is no "heater relay." You mean the blower resistor, it is mounted on the heater box and sticks down inside in the airflow to keep it cool. It might be miswired, or shorted to ground.

I show a black/ tracer going to the heater switch from the fuse panel

A brown and a dark green go from the switch to the resistor. The motor hooks up there as well.

You can check out the switch by disconnecting bot switch wires from the resistor, and jumper them one at a time to the motor lead. The "med" switch setting when connected, as well as "high" when connected should make the motor run at high speed.

What is not shown in these diagrams, or for that matter, the downloadable shop manual, is how the motor connects to the resistor.

http://www.mymopar.com/downloads/1966/66ValiantA.jpg

http://www.mymopar.com/downloads/1966/66ValiantB.jpg

 

[RedFish]

Each resistor is fired through the fan control switch. 2 screws to remove then lift the resistor pack to visually inspect. I'm almost certain you will find the fault to be in the switch.