Blend door heater blows cold air?

2008 BUICK LA CROSSE
108,000 MILES • 3.8L • 6 CYL • 2WD • AUTOMATIC
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BMCMURTREY
  • MEMBER
  • 1 POST
Heater blows cold air. Both hoses are hot, so there is coolant flow.
Nov 25, 2025 at 6:28 PM
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STRAILER
  • ✓ASE Certified Mechanic
  • 54,832 POSTS
  • ASE Certified Mechanic
I would make sure the coolant level is full, (engine cold only). Even though you feel coolant (hot) the flow rate can be low because of a clogged heater core, you might want to remove the hoses and flush it using a garden hose. I don't think it is a blend door actuator because both sides (right and left) would need to be bad at the same time. This does have dual range climate control correct?

Here is a video to help

https://www.youtube.com/watch?v=SNRb6pSwYuU

Please upload a short video in your response of the problem, so I can see what's going on :)
Nov 26, 2025 at 10:52 AM
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