I was wondering what might cause this. I have a few ideas but wanna see if anyone elses ideas are similar to what I am thinking so I have a better idea of where to start. When the A/C is on the air blows really nice and cold like it should but idling at a light or in park it starts throwing warm air until you start moving again. Same thing with the heater, when your moving its blowing nice and hot until you stop then it cools down til you take off again. Anyone know right off what this could be, or atleast can I get a few guesses to see if they are what I was thinking. Thanks alot.

 

thats interesting.maybye your heater core is partially blocked? when you step on the gas the water pump is able to push the coolant past it?? the a/c i have no clue what that could be.id say blend door but it would be doing that all the time probably.

 

My vote would be blend door problem. What ever it is you will have to crack that dash open to see.