Front heater intermittently not working

2004 CHEVROLET TAHOE

190,000 MILES • 5.3L • V8 • 4WD • AUTOMATIC

RAGINGSOUL

MEMBER
54 POSTS
FOLLOW

When I started the truck and turn the heater on nothing was working. the back heater works fine you can hear the motor blowing the hot air but the front is not. I started driving down the road and the heater came on. I came back out started the truck up and the heater is not working. I started the truck and was letting it idle then the heater came on and now it's turning on shutting off turning on shutting off. What would be causing this a fuse and if so would it be the one underneath the hood?

Mar 23, 2021 at 6:45 AM

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KASEKENNY

AUTOMOTIVE REPAIR CONTRIBUTOR
18,907 POSTS

This could be a couple of things but most likely sounds like the blower motor process (resistor).

https://www.2carpros.com/articles/car-heater-not-working

The way to confirm this is check the power at the blower when it is not working. We can be pretty confident that it will be 0 volts.

Then we need to go to the processor and check each wire for voltage. I suspect we will have 12 volts coming in but nothing coming out which means it needs to be replaced.

https://www.2carpros.com/articles/how-to-check-wiring

Below is the wiring diagram and the process from the manual that will help with this if this proves out.

Let me know if you have questions. Thanks

Images (Click to enlarge)

Mar 24, 2021 at 5:12 PM

RAGINGSOUL

MEMBER
54 POSTS

KASEKENNY1, Thank you very much I will read and follow and see what I come up with.

Mar 28, 2021 at 3:54 PM

KASEKENNY

AUTOMOTIVE REPAIR CONTRIBUTOR
18,907 POSTS

Sounds great. Please let us know what turns up. Thanks for using 2CarPros.

Mar 29, 2021 at 7:25 PM