Heater core replacement

SWILLIAMS

MECHANIC
597 POSTS

The ENTIRE dash comes out. There are screws behind the speakers on each side and behind the defroster vent. Pls some on each end underneath and at the center where the console is.
You also need to drop the steering column.

Get a new core. They are not usually worth repairing.

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Sunday, October 25th, 2020 AT 12:19 PM (Merged)

SERPENTRACER

MEMBER
34 POSTS

Does the hoses of the heater core get hot?
If they don't you need to flush it out or bleed the system better/more.

If they do then you can start looking into the controls.
Vacuum operates all the doors of these trucks.

A common problem with these trucks is a bad vacuum line. They go into the cab near the brake booster.
Rubber vacuum lines on these trucks seem to last about 4 years.

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Sunday, October 25th, 2020 AT 12:19 PM (Merged)

KHLOW2008

MECHANIC
41,814 POSTS

Here is a flow chart for troubleshooting. See if you can come up with any information that might help us get to the bottom of this.

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Sunday, October 25th, 2020 AT 12:20 PM (Merged)

TARCHER

MEMBER
1 POST
1991 GMC SONOMA
4 CYL
2WD
AUTOMATIC
45,000 MILES

Heater core removal from inside cockpit or through fender well?

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Sunday, October 25th, 2020 AT 12:20 PM (Merged)

MASTERTECHTIM

MECHANIC
4,750 POSTS

From inside the cock pit. Remove passenger side lower hush panel and glove box. Remove cover to access heater core. **Fairly easy job for the do it yourself mechanic.