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Old 09-13-2018, 10:57 AM   #1
67chevy40
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Join Date: Aug 2018
Location: Kalamazoo Michigan
Posts: 6
67 Chevy c10 heater and ac

I’m not sure how to wire my heater and ac with my new wiring harness. I only have one wire that says heater which I believe should go to the heater fan however the plug behind the controls is burned and needs to be redone. I no longer have the ac because the owner before me took it out when he put in a bigger motor instead of the original v6. He replaced it with a v8 small block. I just need help with how to wire the switch and heater fan.
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Old 09-17-2018, 01:16 PM   #2
LH Lead-Foot
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Join Date: Jan 2018
Location: Omaha, NE.
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Re: 67 Chevy c10 heater and ac

The heater for a 67 C10 uses a BRN wire from the fuse box. Should be hot with key on. This supplies voltage to the heater fan switch. From there 3 wires got into the resistor block for 3 fan speeds. LT BLU is low fan to largest wire resistor in the block. YEL got to the smaller wire resistor for medium speed, the ORG go to one connector at the resistor block, but is crimped with an ORG wire to fan. So the ORG is battery available for high speed. The resistor block is designed to have voltage drops across wire wound resistors to create to different voltage drops. The point where both connect together is terminal for the fan, along with high or full battery B+ from fuse box, to switch, to resistor block, then fan.

So fan switch has 4 wires, resistor block has 3, fan get 1 and grounded thru the body the fan and best to have jumper to chassis ground as the air distribution box maybe fiberglass reinforced plastic.

Make sure to place the resistor block into the air box to have the fan blowing air across it. The wire wound resistor wire gets real hot, real quick and will melt without air flow across it. I think they used a 20 amp fuse for the circuit.

Note; These are factory colors, but may vary on aftermarket harness.
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Old 09-18-2018, 09:41 AM   #3
67chevy40
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Join Date: Aug 2018
Location: Kalamazoo Michigan
Posts: 6
Quote:
Originally Posted by LH Lead-Foot View Post
The heater for a 67 C10 uses a BRN wire from the fuse box. Should be hot with key on. This supplies voltage to the heater fan switch. From there 3 wires got into the resistor block for 3 fan speeds. LT BLU is low fan to largest wire resistor in the block. YEL got to the smaller wire resistor for medium speed, the ORG go to one connector at the resistor block, but is crimped with an ORG wire to fan. So the ORG is battery available for high speed. The resistor block is designed to have voltage drops across wire wound resistors to create to different voltage drops. The point where both connect together is terminal for the fan, along with high or full battery B+ from fuse box, to switch, to resistor block, then fan.

So fan switch has 4 wires, resistor block has 3, fan get 1 and grounded thru the body the fan and best to have jumper to chassis ground as the air distribution box maybe fiberglass reinforced plastic.

Make sure to place the resistor block into the air box to have the fan blowing air across it. The wire wound resistor wire gets real hot, real quick and will melt without air flow across it. I think they used a 20 amp fuse for the circuit.

Note; These are factory colors, but may vary on aftermarket harness.
Thank you I believe they are still the factory wires but a few of the lugs are melted so I’m going to replace all of the wires and plugs myself I just wasn’t sure where everything went. Thank you again for your help.
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