Chrysler Repair: 95 Acclaim heating; only heats when moving, coolant level, radiator cap

Question
My 1995 Plymouth Acclaim heater blows cold air when idling but hot when driving.

Answer
Hi Greg,
I believe that you have air trapped in the upper part of the cooling system. This would be most likely if you have the 2.5L 4 cyl engine. To remedy this, begin with the engine running, and the heater in the red zone,i.e. asking for heat. Then turn off the engine and drain off about 2 or 3 quarts of coolant from the radiator allowing the fluid to be sucked from the overflow bottle first and then if necessary remove the radiator cap. Collect the coolant for reuse. Then open the plug (6 mm allen head) on the top of the thermostat housing located just below and between the 3rd and 4th spark plugs. Then begin refilling the system from the radiator cap opening and watching until the coolant level rises to the top of the thermostat housing.
Then with the housing full to the top, replace the plug and continue fill the system until the radiator is full and add addition coolant to the overflow bottle as shown by the level marking.
That techniques should remove the air bubble and restore your heating function.
Roland