No power to heater fan switch or to fan relay except for red wire

[bananaman]

I need some help. When I turn the key on I have no power to the fan switch or to the high speed relay except for the red wire which is constant. This is on a 1979 GMC jimmy. Can anyone point me in the right directions?
Thanks

 

[AuroraGirl]

I need some help. When I turn the key on I have no power to the fan switch or to the high speed relay except for the red wire which is constant. This is on a 1979 GMC jimmy. Can anyone point me in the right directions?
Thanks

Fuses. they are glass on yours.
The pigtail under the hood.

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I have a 1980, also dont ask whats happening, lol, but I also have no AC. I found that brown wire when interupted will work as an on-off for the fan in my truck.

 

[bananaman]

My fuses are not glass. All fuses are good.

 

[AuroraGirl]

My fuses are not glass. All fuses are good.

My bad, 79 was the first year of blades. 1978 was the last year of glass.

does your truck have AC? Im not sure of this red wire you speak of. Engine bay wise?
If you have non AC truck, the picture of mine is a good reference you should see power on that brown wire in the corner when key on.

 

[bananaman]

Yes mine has A/C.

 

[AuroraGirl]

Yes mine has A/C.

im not the expert to ask here then.

heat/AC wiring diagram

heat/AC wiring diagram

forum.73-87chevytrucks.com

This MAY be for your truck, I found it on this thread I linked

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[Snoots]

Get a DMM and check for voltage at the heater fuse, both sides. Voltage is like water plumbing; just follow the flow.

 

[bananaman]

I have 12 volts on each side of fuse.
Still no power on the orange or purple wire. I have installed new new relay,resistor and fan switch and heater AC controls.where does the orange wire get its power from?

 

[Snoots]

IIRC, Orange is constant hot, purple is acc/ign only.