86 gmc C1500 Blower motor won’t turn on?

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Billys44s

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Jul 5, 2021
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Location
Mcalester Oklahoma
First Name
Billy
Truck Year
1986
Truck Model
High sierra
Engine Size
400 Sbc
So I’m having an issue with my blower motor, I just bought a new one a few weeks back and it worked for the 1st few days but it suddenly stop powering on, so I decided to do some digging and if I hook a wire straight up to power it comes on but if I use the fan controls inside the cab, nothing happens, I Checked the main power wire going to the plug and it gets 12 volts while the switch is on but the blower motor still doesn’t do anything
 

CheemsK1500

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Jun 3, 2022
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747
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Location
Texas
First Name
Paul
Truck Year
1984
Truck Model
K1500
Engine Size
305
Edit: misread post. I'd suggest removing the HVAC switch from your dash, and tracing the wires.

I once had a bullnose Ford pickup that had this same problem. It ended up being the ignition switch on the steering column. On many vehicles, most of the key-on devices power (such as the blower motor) originates from the ignition switch.
 
Last edited:

Arizona Ranger K5

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Nov 11, 2022
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Location
Tucson, AZ
First Name
Harper
Truck Year
1981
Truck Model
K5 Blazer Silverado package
Engine Size
350/TH350/NP208/GM12/4.56
There is a "heater fan relay" on the outside of the a/c box (on my '81) and there is also a "heater fan resistor" in the top of the a/c box. heater fan resister I believe controls speed setting, relay controls operation of fan. I have to change out both of mine.
 

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