Heater is blowing cold

[hyde]

Wow, it is blowing cold/cool air even at HOT. If I am moving fast and turn it on it blows warm/hotter air but if I stop and turn it on or turn dial to red (hot) section, it won't blow. I can feel it, blowing A/C and not just flow-through.
What's wrong with this thing now?

 

[tjkj2002]

Wow, it is blowing cold/cool air even at HOT. If I am moving fast and turn it on it blows warm/hotter air but if I stop and turn it on or turn dial to red (hot) section, it won't blow. I can feel it, blowing A/C and not just flow-through.
What's wrong with this thing now?

Either you got a vaccum leak in the HVAC unit or a leak in the main blend door,hence when going fast it open the heat side and closes when slowed down.Could be a bad blend door acuator also.Just some places to start looking.

 

[hyde]

Thanks tj, are those in spots that can easily be checked from the under the hood? I feel like this happened after driving through deep waters last week.