Guys,
Finally getting around to troubleshooting my blower motor on my 67. But I am not entirely sure when it would be on. I assume the top slider is the switch for it. Since it doesn't have the fan speed switch like an AC car does. I have confirmed that I don't have voltage at the fan with the top switch to the on setting. Is that all that needs to be on? Or does the heater switch or defroster need to be in a specific location?

Sorry for the novice question. I guess if I had an owners manual I could tell. Now I need to troubleshoot back from the fan and find the relay or switch that may have went south.

If anyone has any guidance I'd apprecite it. Need to find the proper schematic in the AIM.

Dave

Jumped the fan and it works just fine, just need to reverse engineer the current. But still wonder about just when it should be on.

Dave,
are you asking how far you have to move the slider before the fan comes on? not sure, i think low speed might be around the halfway point? it doesn't matter where the temperature or defroster sliders are, they just control some flappers in the heater box and have nothing to do with fan speed. In addition to the switch in your dash controls, there is also a blower resistor mounted to the top of the heater box. it's basically two coils of high resistance wire. all you see on the top side of the heater box is the prongs that the plug connects to. the little coils are on the bottom, inside the heater box. The switch that's controlled by the slider in the heater controls determines which coils to put current through.

-slider all the way to the left = switch off, fan doesn't run
-slider at "low" position = current goes through both resistance coils, low voltage delivered to motor, fan runs slow
-slider at "middle" position = current goes through one resistance coil, a little more voltage delivered to motor, fan runs a little faster
-slider at "high" position = current bypasses resistance coil, full voltage delivered to motor, fan runs at high speed

I don't have a schematic in front of me so i can't tell you where specifically to check for voltage (the AIM has schematics). I would definitely take a look at your blower resistor on the top of your heater box.

Thats some great info Aaron, I had assumed it was an on off switch and not variable. I found the resistor in my AIM Wiring it isn't entirely clear on which lead is energized in each position. I'll do some searches and see if anyone has any writeups on diagnosing that. I probably need to go from the switch downstream knowing these resistors are involved.

This is the info i was looking for. Ask the right question and the SEARCH will find your answer. Can you link this post from another post?