The heater will blow hot and all at once start blowing cold

2007 DODGE RAM
30,000 MILES • V8 • 4WD • AUTOMATIC
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DODGE1
  • MEMBER
  • 1 POST
The heater will blow hot and all at once start blowing cold. Then the heat gauge starts to go up and truck tries to overheat.
Dec 8, 2010 at 6:18 PM
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DOCFIXIT
  • ✓ASE Certified Mechanic
  • 18,828 POSTS
  • ASE Certified Mechanic
Hello,

It sounds like you have a blown head gasket which filled the heater core with exhaust gases which makes the heater stop working here are two guides to help us get started.

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

and

https://www.2carpros.com/articles/head-gasket-blown-test

Please run down these guides and report back.
Dec 8, 2010 at 6:25 PM
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HLACEFIELD
  • MEMBER
  • 1 POST
I had the same problem and had to replace the blend door actuator.
Jan 7, 2019 at 6:53 PM
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