Heater

C&R

MEMBER
1987 CHEVROLET 2500
7.4L
V8
4WD
MANUAL
250,000 MILES

No power to heater switches and to the blower fuses are good.

Thursday, September 21st, 2017 AT 4:27 PM

7 Replies

WRENCHTECH

MECHANIC
20,758 POSTS

Are you sure about the vehicle description. They did not have a 2500 or a 7.4 engine in 1987.

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Thursday, September 21st, 2017 AT 6:08 PM

C&R

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4 POSTS

1987 Chevrolet with a 454 throttle body and it is the six pack on the side of the truck says 30 that is all.

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Thursday, September 21st, 2017 AT 6:22 PM

C&R

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4 POSTS

I do not have no power to the controls or any wires of the wires. I have changed fuses and checked the fusible link. I have traced all wires no broken ones.

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Thursday, September 21st, 2017 AT 6:28 PM

WRENCHTECH

MECHANIC
20,758 POSTS

I found it under R30. The blower motor is powered and controlled by the blower relay and the relay is powered and controlled by the blower switch through the blower resister. The blower switch gets its power from the ignition switch so you are going to have to track down where it is being lost.
I uploaded the wiring diagram for you.

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Thursday, September 21st, 2017 AT 6:36 PM

WRENCHTECH

MECHANIC
20,758 POSTS

This one might be clearer.

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Thursday, September 21st, 2017 AT 6:41 PM

C&R

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4 POSTS

Thank you.

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Thursday, September 21st, 2017 AT 6:46 PM

KEN L

MASTER CERTIFIED MECHANIC
43,262 POSTS

Here is a guide to help you do the testing:

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Please let us know what happens so it will help others.

Cheers, Ken

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Saturday, September 23rd, 2017 AT 2:03 PM