Chrysler Repair: Heater Problem, coolant level, matter weather

Question
The heater in my 2005 town and country only warms up when the gas pedal is pressed. It only blows cold air until you start driving. When you stop at a light, there is a definite temperature drop in the air flow. Also, the air in the rear system does not always flow. It is a dual zone system. I am checking the antifreeze today when I get home(wife's vehicle). I have read your other posts and understand it could be an actuator motor or blend door issue. If it is not the fluid, what is your next suggestion? And should I just bite the bullet and take it to the dealer?
Thanks for the advice,
Kent

Answer
did u check in the radiator  not the over flow tank?  the heating system in mechanical with fluid not electrical it does not matter weather or not the van is in motion the same amount of coolant is being pushed to teh heater core and the blend air door motors stay the same inside.
Look at the coolant level in the radiator