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Old 03-04-2020, 02:22 AM   #1
toolboxchev
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Heater Switch Issues

So I feel like a dumby on this one. First images shows a highlighted area. Its marked as Air Cond 25 amp. Does the heater run off this also if I have no AC?

Or do I put a 10 amp fuse in this location???

Or in the second photo, does the actual heater run off a 3 amp fuse? In the location under the AC circuit.

I keep blowing the heater switch, most likely in high position and the wiring harness. My electrical is all jacked up due to water intrusion, missing markings on my panel in the truck.

Thanks in advance.
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Old 03-04-2020, 04:14 AM   #2
randy500
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Re: Heater Switch Issues

The brown wire at the heater or AC switch goes directly to the fuse,
Insert 10amp fuse for heater only
Insert 25 amp fuse for AC

The brown wire to the switch is the same for heater or AC, heater or ac wiring harness continues off from the switch at the heater or ac panel.
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Old 03-04-2020, 04:20 AM   #3
randy500
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Re: Heater Switch Issues

I just noticed the labeled fuse box picture...its labeled wrong.
First pic orientation which is readable is better, label is below all fuses, except AC which is optional and has its own fuse rating.

Little arrows from fuse name point to fused terminal too. Radio and pnl lights
Pnl lights is for tilt column indicator lamp and dims with dash lights.
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Old 03-04-2020, 04:21 AM   #4
randy500
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Re: Heater Switch Issues

If your blowing fuses i bet your blower motor is about to seize up, high amp draw probably due to bad bearings.
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Old 03-04-2020, 01:43 PM   #5
toolboxchev
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Re: Heater Switch Issues

Hey Randy,

I am suspect to the labeling also. For clarification the 2 pics are opposite of each other, or one upside down to the other.

My fan is a newer unit from AutoZone FLAPS, 20 dollar lifetime unit approx. 3 years old, no squealing of bearing.

The fuse in location in the middle of AC and BU light goes out I lose my heat fan.


I know I have something funny going on. Still working it. Thank you.
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Old 03-05-2020, 01:08 AM   #6
toolboxchev
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Re: Heater Switch Issues

Well, thought to post an update. Turns out your right, thank you!

Cleaned up the fuse block with wire brush, new fuses, checking wiring.

Put a 10 amp in the Heat & AC Location, tested, worked first time, turned off. Turned on again and boom, fuse blew. Wired brown wire to a new switch, directly to blower fan.

15 amp in there now and its still functioning.
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Old 03-06-2020, 02:36 PM   #7
toolboxchev
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Re: Heater Switch Issues

Well, cooked the wiring under the dash yesterday. Got a new ignition switch, Blower Fan (non AC) unit from Napa.

Chasing down more parts. Some one told me there is another resistor on the actual blower motor of stock applications. Any one know if this is true?
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Old 03-16-2020, 01:55 PM   #8
Dead Parrot
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Re: Heater Switch Issues

On the motor, no. Between the motor and the switch, yes. Normally close to the motor with the coils in the air box.
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