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Old 07-01-2020, 09:52 PM   #1
57taskforce
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No power to blower motor.

I’ve read several threads trying to diagnose my issue with no success. I can’t get power to the purple motor feed. 72K20 with factory AC.
I’ve got power to the switch, the relay clicks when I switch it off of high speed, I’ve got power to the blue wire at the relay and the small orange stand alone wire on the relay.
I’ve got power to the double yellow wires on the resistor.
All of this and I’ve got no power to the blower motor as verified with a multi meter and test light both (grounded to the negative batter terminal) on the purple motor feed wire.
Is my resistor bad and relay both bad?? I’m pretty good with electrical stuff but I can’t seem to make heads or tales of this.
Any suggestions?
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Old 07-02-2020, 03:19 PM   #2
Richard
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Re: No power to blower motor.

Need to rule out the mechanical devices. Seeing as you have a multimeter I would disconnect wires from resistor and ohm it out. Apply 12v to the coil on the relay and ohm it out as well. If the switch is older may want to check that as well.
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Old 07-02-2020, 07:02 PM   #3
dmjlambert
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Re: No power to blower motor.

The 12 gauge Orange wire at the relay should have power, because it should be plugged into the fuse box face. Usually plugged in the CIG position. When the relay is energized because you have the switch in high position (all the way down), the relay contacts connect 12 gauge wire to the 12 gauge purple wire. The resistors and other stuff are bypassed.
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Old 07-02-2020, 11:28 PM   #4
57taskforce
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Re: No power to blower motor.

Thanks guys. I didn’t have any time today to work on it as my wife had me doing honey do’s. I’ll check the orange wire at the fuse box tomorrow. I’m sure it’s something simple. Richard, about the only other thing I haven’t done is to ohm everything out as I ran out of light yesterday evening. I’ll got that tomorrow as well. My Fluke has been getting a workout the last couple days.
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'72 K20 Cheyenne: 5” lift, 35’s, front dana 60 blah blah blah… http://67-72chevytrucks.com/vboard/s...d.php?t=662879
‘69 K10 SWB: 4” lift 33”s… in a million pieces http://67-72chevytrucks.com/vboard/s...d.php?t=805206
'98 Silverado LT K2500HD ECLB Vortec 454/4l80E: 6" lift 35x12.5x20’s
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Old 07-04-2020, 01:02 AM   #5
57taskforce
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Re: No power to blower motor.

I got some more time to play with it today and I finally was able to get power to the purple motor feed wire. The orange wire that feeds the fan relay wasn’t making good connection. After all that... the damn blower motor is bad lol. I got to get some parts coming.
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'57 3100 http://67-72chevytrucks.com/vboard/s...d.php?t=813888
'72 K20 Cheyenne: 5” lift, 35’s, front dana 60 blah blah blah… http://67-72chevytrucks.com/vboard/s...d.php?t=662879
‘69 K10 SWB: 4” lift 33”s… in a million pieces http://67-72chevytrucks.com/vboard/s...d.php?t=805206
'98 Silverado LT K2500HD ECLB Vortec 454/4l80E: 6" lift 35x12.5x20’s
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