heater blows cold air when at idle even when temp is at normal?
when the car is accelerating it blows warm air but as soon as u come to a stop and idle say st a light
it blows cold air ,even if u free rev it ,it stays cold ...Any help please!
The device known as the thermostat is supposed to let the engine warm up, then as soon as the coolant reaches 195 will open up and let the warm coolant circulate thru your heat exchanger...if it never gets up to 195 because it is stuck open, you will have minimal heat, just as you describe....in summation, change the thermostat and all will be skippy in skippy town.
...also 195 is operating temperature...if it never gets there you'll have incomplete combustion, resulting in smokey exhaust and poor acceleration...if you didn't notice.
be sure to have your mechanic 'belch' the heat exchanger or it will become air-bound after the thermostat replacement.
The dampers for the duct work of heating systems are controlled by vacuum. If at idle and car is at operating temp with heater on and you feel air coming out the vents but its cold and without touching any controls you start to drive and warm air starts coming out of them I would check for a vacuum leak going to the controller. As you drive faster the vacuum increases and will provide enough pressure to move the damper but at idle with the vacuum leak not enough pressure there to move it. This vacuum line will be coming from the intake thru the firewall to behind your heater controls. This is what I would check after you check all of what bob stated. Have to have heat in the heater core first.
Sounds like a coolant flow problem. Newer Impalas have electronic motors that control the doors under the dash for air temperature. Could be a partially clogged heater core. HTH. -Jim
Same with my 05 Impala. I changed the thermostat after it started blowing cold air. No improvement. I bled the brass bleeder on top of engine, filled resevoir, etc. It gets warmer the more gas you give it, then when letting off gas goes cold again. Both hoses to and from heater core get hot, so I am at a loss...
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