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

2007 DODGE RAM
30,000 MILES • V8 • 4WD • AUTOMATIC
Avatar
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 10:18 AM
Advertisement
Avatar
DOCFIXIT
  • ✓Experienced Mechanic
  • 18,828 POSTS
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 10:25 AM
Avatar
HLACEFIELD
  • MEMBER
  • 1 POST
I had the same problem and had to replace the blend door actuator.
Jan 7, 2019 at 10:53 AM
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.
Ask a Free Question
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.