heater motor resistor

[oldhalftons]

Is there a resistor that can fail in between the heater fan speed switch and the blower motor? and if there is , where is it?

[68F250]

Yes, if the fan only runs in the "high" position, the resistor assy. has failed. Unfortunately, it is bolted to the back side of the heater box. You will have to remove the whole thing to get to it. The wire wound resistors get hot so they are located inside.

[flyboy2610]

I believe this is the beastie in question.

[67F250CS]

Hope this pic will help a little. It the part that has the wires attached to it. Two small screws hold it on. You can get to it without taking it out but it is half the time to just remove the heater box and all. If you leave it in your working kind of blind as its between the heater box and the firewall and you have about 2-3 inches to work in.

[oldhalftons]

thanks a lot

exporitory surgery continues.

Its getting cold in the mornings and I have no heater fan on any speed and the fuse is good .

All this stuff worked when I bought the truck, my electrical system is self destructing

[68F250]

Thanks guys for posting the pics!

67F250CS, I stole your pic if you don't mind. Oldhalftons, you can test the blower motor by itself. See the two wires I'm pointing out? The orange one is the "hot" to the blower and the black one is the blower ground. Try disconnecting the orange wire at that connector. Pull on both sides of the connector, don't yank the wire by itself as you can easily break the resistor assy. Now apply 12 volts so it goes directly to the motor and see if the fan turns. If it doesn't, check the ground wire.

[67F250CS]

No problem. In fact I was going to put some lines on that photo but the free trial of photoshop has expired.
Any help to any member is fine with me.

[68F250]

Great! I was hoping you'd feel that way.

Since the blower doesn't come on at all I'm starting to believe it's the motor.

[oldhalftons]

good, the motor looks easier to change

[flyboy2610]

The wheel is held onto the motor shaft by a set screw. Soak the hole in the wheel where the shaft is with some penetrating oil, then the wheel should slide off the shaft with a good tug.

[oldhalftons]

well,
I have no power to that orange wire at the fan, but the motor turns with direct power

I guess I have to start taking things apart and check the heater fan switch too now .

[fordman]

yep just follow the power backwards now to see where you lost juice from. when you find power the trouble is between there and the fan
you probably already know this though.

[oldhalftons]

yup, I knew it, I was just hoping to avoid it though.

[flyboy2610]

At least you won't have to spend $55-60 replacing the heater motor.
Like I have to.