I just got an 03 Civic SI a couple of days ago. When the car is warmed up and driving down the road the heat blow hot but as soon as I stop at a stop sign or red light within seconds it starts to cool off and blow cooler air. Winter is coming up so i would like to get this fixed ASAP. Any help would be great thanks in advance.

BTW it has 43K miles on it.

 

go talk to the dealer about it.

 

this may sound dumb but i had a toyota that did the same thing when it was low on coolant...

 

Fixed it. It was just a little low on coolant. Thanks for the advice.