Whats goin on guys, i've had a problem with my 00' Impala and its heater. Whenever i get in my car and start driving weather its the early morning, middle of the day, or at night and i go to turn my heater on Settings 1,2,3,4,or 5 all i feel is cool air. The odd thing is whenever i accelerate i feel the hot air come through the vents and im not sure if its due to the cooler air pushing the hot air into the cabin or something that effect the heating system while i accelerate. Any advice would be appreciated, thanks Pat_OD