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Dec 30, 2020 | 10:02 PM

Tony53

Thread Starter

Heel & Toe

Joined: Apr 2020

Posts: 23

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From: Oakdale NY

Need Your Help

Hello to all: New to the forum I have an 80 with a 350 crate motor, stock except for Edelbrock Carb and Manifold. Have a weird issue. Start the car, put the blower on high, nothing, open either side door blower turns on, close door blower goes off. Installed new blower relay, checked fan wiring, installed new door pin switches. Even removed the fuse for dome/courtesy lights still happens. Checked all the fuses, all ok. Block ground is good. Completely mystified. Any ideas are appreciated.

Dec 30, 2020 | 10:41 PM

Vette_DD

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Dec 30, 2020 | 11:42 PM

Vetteman Jack

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Jan 1, 2021 | 09:52 AM

Eliredandblack

Melting Slicks

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From: Marietta GA

You need a wiring schematic for an 1980 car. Then start looking/tracing all wires (by appropriate color) going to the blower relay, switch, and blower. I will take a Wild guess ... could be a ground attached to the wrong terminal. Is the electrical harness OEM?

Jan 1, 2021 | 11:10 AM

randallsteel

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In general, blower motors always have 12v supplied(with ignition on) and the speed switch connects the motor to differing resistances or straight to ground. It sounds like the ground for the blower motor is misplaced. When the doors are opened, the door jam switch connects the interior lights to ground. It seems that the blower motor is sharing this circuit. You can test this by just taking the ground terminal for the blower motor and grounding it. If the fan operates when the ignition switch is turned on then you know it’s an issue with the ground circuitry. Then it’s just tracing that and seeing where it’s connected too.
Pulling the fuse for interior lights just removes the 12v supply to the lights, the door jam switch still connects the ground side to ground, which will still complete the circuit for the blower motor, which appears to be sharing the same ground circuitry.

Jan 1, 2021 | 11:37 AM

80VETENG

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Joined: Jun 2006

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You may have a bad Ground on the Engine Harness which is grounded through the Starter Harness (6 position connector located on back of engine along the bellhousing kind of on the passenger side) the Starter Harness should have a couple of Black wires attached to a ring which should be grounded to the bellhousing by the starter (I believe)..... This provides ground for A/C compressor, Fan, Fan resister etc.... without it these devices would receive ground through the Hood Alarm Switch circuit which is tied into the door switches when the doors are opened..

Jan 1, 2021 | 12:12 PM

Tony53

Thread Starter

Heel & Toe

Joined: Apr 2020

Posts: 23

Likes: 3

From: Oakdale NY

Thanks, as you know the blower is in a tough location, but I will start there and trace all wires. Appreciate your advice

Jan 1, 2021 | 08:01 PM

Tony53

Thread Starter

Heel & Toe

Joined: Apr 2020

Posts: 23

Likes: 3

From: Oakdale NY

Thanks to all. The problem was as many of you stated the ground for the blower motor. Wasn't able to trace the original ground wire, so I installed a new one, and everything is working fine. When time allows, and the weather is warmer, I do want to try and locate the original ground.

Tony53