2007 Chevrolet Uplander heater won't blow warm air when car is stopped or parked but will when moving

Check your engine coolant level in your 2007 Chevrolet Uplander. My guess is it's probably low. Your heater core uses the heat off of your engine provided by your engine coolant.

Sounds like you are low on antifreeze. If the level is low, the car does blow cold when the car is idling. Most likely this is an inexpensive fix that should remedy your problem.