I have a 03 civic. When I am traveling on the highway my car will produce good heat. When I stop or even slow down it begins to blow cold air and the temp. gage is in its normal position. Can you tell me why its producing cold air when it should be hot air. Thanks.

 

I am also having the same issue with my 03 civic. Any ideas??????

 

possibly not enough coolant going through your heater core to heat it up enough to your desired level since it is so cold out. bad thermostat?

 

If your engine is K20, I would say most probably it's the belt. Check and tighten if too loose.

If not - partially blocked heater core would be my second best guess.

 

Tater, thermostat has nothing to do with heater circuit, get your car first, then try to advise others.

 

Is the 03 heater computer, or manual cable controlled?

 

the thermostat closes off to allow the water in the block to heat up and then opens at a certain temp to allow the water to move into the heater core. if the thermostat sticks open, then the water does not heat up enough to give hot air.
to the both of you, take the thermostat out and check in a pan of boiling water

 

forget checken the dam thing... just replace it with a hoter thermostat.... and when spring comes change it back to stock temp thermostat....
ive always got to do that with my truck... in the winter its just hard as hell to heat up!


but if ya dont want to do all of that just keep your air on recirculate....