Cold Air When Idling

11-29-2011, 08:37 PM
What would cause my heater to blow cool air when idling, but warm/hot air when driving?

I'm baffled.

Thanks in advance.

Tech II
11-29-2011, 10:06 PM
Well, it sounds like a vac problem....but the way you describe it, is the opposite of what I would expect...if your temp valve is vac operated, and the check valve to the vac tank is bad, you would lose vac at open throttle, and would gain vac again at closed throttle......

11-29-2011, 11:46 PM
Have you checked your coolant level ? That can cause the scenario you have described .

Tech II
11-30-2011, 09:58 AM
What is your temp gage doing?

Blue Bowtie
12-04-2011, 10:56 AM
Is the water pump impeller eroded? I've seen that more than once.

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