heater blows cold air when at idle even when temp is at normal?


Asked by Mar 09, 2013 at 11:50 PM about the Chevrolet Impala

Question type: Maintenance & Repair

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!

26 Answers

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.

22 of 22 people found this helpful.

...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.

8 of 8 people found this helpful.

be sure to have your mechanic 'belch' the heat exchanger or it will become air-bound after the thermostat replacement.

15 of 15 people found this helpful.

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.

30 of 30 people found this helpful.

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

6 of 6 people found this helpful.

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...

63 of 63 people found this helpful.

Sounds like the air temperature door under the dash isn't working correctly. HTH. -Jim

12 of 12 people found this helpful.

I am having the same exact problem in my 05 Grand Prix... going to change the thermostat tomorrow.

6 of 6 people found this helpful.

My car is always doing the same thing. Blows hot air until I stop. is this a Chevy thing or what? I have a 2007 Saturn aura, same as a Chevy Malibu .

12 of 12 people found this helpful.

I wish I new what was going on. I changed my thermostat, radiator, radiator cap, anti freeze, and I still have the problem. At idle, its cold air. driving down the road, warm air. I have a 1995 Mitsubishi Montero SR that I purchased new. A great machine, but this is puzzling.

19 of 19 people found this helpful.

I've been having the same issue with my 2007 impala. Done many coolant flushes and replaced thermostat. Recently had it flushed again, heater was working for about a month now it's blowing hot air only when I'm hitting the gas. Been having this issue for two winters now. My mechanic has no idea what's going on. thinking about replacing heater core? Any suggestions?

56 of 56 people found this helpful.

I fixed this issue for good in my grand prix. What it is is the coolant isnt being filled properly. Try running the vehicle for 5-10 minutes with your radiator cap off, and after it has been circulating for a little bit, fill it with coolant from the open cap and allow it to fill up your coolant container. This will flush out your bubble and solve you problem. At least it di for me...

17 of 17 people found this helpful.

I took mine in. It was a blown head gasket. Thank god it was still under warenty. It would have been close to 2 grand

7 of 7 people found this helpful.

I have tried several things on my 07 Impala. Total tune up including new thermostat. Nothing. Just had the heater core replaced, still no hot air when idling. Not over heating so no water flow problem. I will try the radiator, cap off while idling, adding coolant directly to opening and see what happens.

9 of 9 people found this helpful.

I changed my thermostat n my 2009 impala and done a flush and then my car started to do right on heat

6 of 6 people found this helpful.

This problem has happened on all 3 Impalas I have owned. It is none of the problems listed above---The engine coolant cross over pipe and gasket needs to be changed. Chevy has had problems with this for years. There currently is a new design that plugs the hole, but not so for the older models. The part numbers are 000000000012623852 and 000000000012623853 and 000000000012346290. The parts cost around $50.00.

10 of 10 people found this helpful.

I have the same heating issue and have done all of the above. I believe this is a Chevy issue that they need to do a recall on.

5 of 5 people found this helpful.

I'm not sure if they have done a recall on this, but there has been bulletins on it. You can ask your dealer to pull the bulletins. My car is by far no longer under warranty, but each of the previous times it has been covered under warranty.

2 of 2 people found this helpful.

I have owned two 2007 Impalas and both had the problem with going cold at idle.My mechanic found out there is a high spot in the radiator hose that can hold an air pocket.He does a procedure with a funnel in the radiator while it's running to get it out.I believe it has some kind of a seal at the funnel so the coolant can be higher than the air pocket

5 of 5 people found this helpful.

If it was an air bubble in the system the heat gauge would fluctuate when the bubble went through the motor wouldn't it? I am having this problem with my 07 impala what should I start with to attempt to fix it

1 of 1 people found this helpful.

I have a 2001 Chevy Impala .I had the problem with cold air blowing at idle. I took off the radiator cap and filled the radiator to the top and got rid of the air bubble. I filled the reservoir to the line now I have heat on idle. that fixed my problem. I wish everything could be this easy.

2007 has a actuator right behind the glove box. It regulates the amount of heat the heater puts out. this is usually the problem with the heater.


Wife started the Impala this morning and had no heat. Blowing only cold. Of course with the temps in the twenties, she wanted me to fix it. Mr. non-mechanical, can change oil and tires only kind of mechanical. After looking this column up, I added water to fill the radiator all the way up (only took a few ounces directly) and filled the overflow reservoir almost all the way up (it was empty). I started it up and it began blowing hot air with a minute. So, Mr. non-mechanical is a hero. Thank you guys!

2 of 2 people found this helpful.

Fill reservoir all the way up, while the car is off remove coolant cap on the passenger side fill with water, once full squeeze top radiator hose at highest point, release squeeze release squeeze as water recess fill it up again re squeeze release squeeze as you do this you notice air bubbles come out as you squeeze re fill keep repeating until it's full and no big bubbles when you squeeze then with the cap off start the vehicle and pour water in as it over flows for about 3-5 sec. Then screw cap on. Turn the heater on wait for about 1min then press the gas petal and try to hold it at around a thousand rpm on and off about three times and heat should be blowing out really hot by then.


@Thomas Youre logic was definitely in the right place....but if the weather is freezing temps or below there then please have your coolant tested to ensure it wont freeze now that all that water has diluted it. I had to "burp" my system this morning after a flush 3 days ago and inconsistent heat. Finally had the time to attend to it and get all the air pockets out. I used more antifreeze/coolant rather than water. Hopefully you see this in time and check. If temp gets lower than freezing point of your antifreeze/water it will crack your engine block causing catastrophic failure. Good luck and cheers.

1 of 1 people found this helpful.

I did use 50/50 antifreeze, now I am getting intermittent heat. If I'm driving in town and slowly, I'll have heat. If I'm on a highway and driving fast, then no heat. Do I need to change the thermostat?

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