blower motor problems

[overbrook 67 f100]

I needed to defog my windshield this morning but when I pulled and turned the switch on my 67...nothing. I took the blower motor out thinking it was fried, but when I hooked it up to my battery it worked fine. Could I have a bad switch? Any other ideas for troubleshooting?

[flyboy2610]

Check the fuse before you do anything else.

[basketcase0302]

Blower motor resister-after checking for voltage:
http://www.ebay.com/itm/NOS-68-69-70-71 ... es&vxp=mtr
They're mounted on the heater housing-just can't remember where right now...

[overbrook 67 f100]

Thanks for the input. I'll check the fuses tomorrow before doing anything else.

[mr_josh]

You know, on my old Chevy, the connections to the blower motor and the relatively small wiring provide just enough resistance that the tired motor can't always get itself started. Every fall I have to clean up the ground and the connections at the switch and motor itself (so that they're super clean) so that it'll get itself spinning. But I can touch its terminals directly to a battery and it'll spin up. I suspect if I went ahead and replaced the fan with a new one, I'd only have to clean up all of the grounds / connections every other year instead of every year.

[Joe_68_F100]

The motor could still be going bad. If the insulation in it has cooked to the point the field is getting weak, it won't spin with a load or with the typical leads because it needs more current to do the same amount of work. It should pop the fuse first, but I've found old trucks before with sheet metal screws jammed in the fuse blocks to get a few more turns out something.

[overbrook 67 f100]

Checking the fuse first fixed the issue. But the fan only runs on high. Any ideas? THANKS!

[basketcase0302]

Part#18591 in this schematic, (the resistor)-or your fan switch is bad.

[overbrook 67 f100]

Basketcase0302,

Thanks for the schematic and pointing out the resistor. Can you tell me if it's located on top of the blower motor housing?

[basketcase0302]

Yes, if memory serves me correctly...
If you pull the glove box out-it should be right there in front of you. I'll try to find my picture I took and come back here in a few minutes to edit.
Sorry, but I've slept since then-(about a year ago when I had mine apart).
It's very visible if the resistor is broken, I'd also check for power there while you have it apart. Check for power from the fan switch, (while on all three speeds).

[overbrook 67 f100]

Thanks for your prompt reply. I'll check in a couple days when I return home. It does work on high speed so I assume there's power but maybe the resistor is not working.

[basketcase0302]

No thanks needed, glad to help. We all take so much from the site here-I'm glad to be able to give something back. I was wrong about the location of the resistor. It is in fact on the back side, (toward the firewall) top portion of the heater plenum assembly. Here's the picture, (where the resistor is visible):



Also note: using the [censored] counter what it was intended to be used for LOL!