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Front heater intermittently not working

Tiny
RAGINGSOUL
  • MEMBER
  • 2004 CHEVROLET TAHOE
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 190,000 MILES
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?
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Tuesday, March 23rd, 2021 AT 6:45 AM

3 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 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
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Wednesday, March 24th, 2021 AT 5:12 PM
Tiny
RAGINGSOUL
  • MEMBER
  • 33 POSTS
KASEKENNY1, Thank you very much I will read and follow and see what I come up with.
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Sunday, March 28th, 2021 AT 3:54 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Sounds great. Please let us know what turns up. Thanks for using 2CarPros.
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Monday, March 29th, 2021 AT 7:25 PM

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