C2 67 heater circuitry

[Ed Jennings]

The heater fan on my 67 (with C60) has stopped working on the two low speeds. Runs fine on high speed. After spending quite a bit of time staring at the wiring diagram in the 67 chassis service manual, I know little more than when I started. The motor appears to be fed by a 14 ga orange wire that passes through several connections and is apparently hooked up with a remote resistor(?). I had surmised that the motor might have a separate high speed circuit similar to the C3's but apparently that isn't the case. There are two black wires shown connected to the motor, one connecting to the starter motor, (ground?), and another that simply terminates in space.

Before I start taking things apart to trace out the circuit(s), is this some sort of common malady? Where is the remote resistor (?) physically located?
Any insight would be appreciated.

[Duke W.]

Re: C2 67 heater circuitry

There's a resistor pack of two resistors that cut voltage to the motor for the low and medium speeds. Medium speed - one resistor in series; low speed, both resistors in series. Sounds like they might be burned out.

The resistor pack is located on the front side of the heater case above the left side of the passenger footwell, and there is a three wire harness leading to it from the top side. The actual resistors are inside the plenum so they are cooled by heater air flow, and the connector is on the outside (between the front of the case and the toeboard). The device should be attached with hex head screws. You can probably run continutity tests with it installed or (with a mirror and flashlight) unscrew and remove it for bench test and inspection.

Duke

[Ed Jennings]

Re: C2 67 heater circuitry

Thanks, Duke. I'll check it out.

[Ed Jennings]

Duke, thanks for the tip

Well, the resistor pack comes right out on an air car. Just remove the two screws and lift. The resistors checked fine, but the connections looked pretty funky, really funky to be more precise. I cleaned them and reinstalled. Fan now runs on all three speeds. I had suspected either the risistors or the switch; nice to find something simple for a change.