Pontiac Repair: 2007 pontiac montana sv6, intake manifold gasket, coolant level

Question
There is no heat in cab at an idle.  
It does not matter if it is just warming up or you have been driving for 30 min.

Answer
Hi Ross:

first off when the van is cold check the coolant level make sure the radiator and the overflow are both full. if they are low you have a leak somewhere like a intake manifold gasket water pump or head gasket. if the system is full then the next thing it could be is a plugged heater core. does this van have the rear heat option? if so is there heat in the back? if there is heat in the back then chances are it's a heater core OR the last thing it could be is a temp door issue turn the hvac blower on hi full vent and then switch the havc from full cold to full hot you should notice a change in the amount of air flowing as the temp door moves if there is no change at all then there is an issue with the temp door and or temp door actuator. good luck!