Car Heater Blowing Cold Air

Hi Austin,

I have a 2006 Chevy Impala that I notice is leaking DexCool coolant looks like from the rad. I have had to fill coolant only twice in the rad and overflow, but the cars temp is not overheating.

I am getting very little heat in cab at idle and “warm” with heat on full when driving. Hotter with higher speeds. I checked the oil and thankfully it’s a golden brown. Nothing in there. But there is signs of Dexcool over the fans in front of the rad, but doesn’t feel like it’s coming from a hose. Any ideas?

Thanks, Craig.


Hi Craig,

First thing you need to do is get a cooling system pressure test at your local mechanic or fast lube place. They will basically use an air pump and attach it to your radiator and pump air into the system to help push out the existing coolant to make the leak obvious to the naked eye.

¬†You don’t have heat at slow speeds because there is not enough coolant circulating in the engine to produce the heat. At higher speeds the water pump is working much hard at pushing what ever amount of coolant it can through the engine and heater core inside the dash.

Fixing the leak and topping off with coolant will probably fix both issues.

Please share this with your friends,

Austin Davis

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2 Comments on "Car Heater Blowing Cold Air"

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  1. ricky says:

    2000 s-10 blazer 4.3 4+4 auto matic heater plows cold air tem gage is normal.hearter core dont leak.what is the problem austin davis.

    • By Austin Davis says:

      If the heater is blowing cold air there is either a restriction somewhere in the cooling system not allowing hot coolant into the heater core or the coolant that is flowing is not hot enough.

      When the engine is at normal operating temperature feel the two heater hoses going to the heater core under the hood…they will be on the passenger side. Both of those hoses should be very hot. IF one is hot and the other is cold, then the heater core could be stopped up with rust or some other restriction is there.

      If both hoses are cold or just warm I would suspect either the thermostat is not working properly or there could be a restriction in the radiator not allowing that hot coolant to circulate properly.

      Both radiator hoses should also be very hot, and the upper hose should have pressure on it when you try to squeeze it together with your hand. if no pressure, you have a leak somewhere or a bad radiator cap.

      If there is not enough coolant in the radiator to begin with well that will certainly cause the problem.

      If you still have problems let me know.

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