no heater at idle/heat when driving

[schadd1971]

hi weird problem....when sitting the air blows cold even when engine is at normal operating temp....yet when you start driving down the road the heat starts to come out the vents the van gets cozy like normal...yet if you park and keep the van running you feel the air go cold again....and when You go again..warm again...anY ideas...

[tempfixit]

Originally Posted by schadd1971

hi weird problem....when sitting the air blows cold even when engine is at normal operating temp....yet when you start driving down the road the heat starts to come out the vents the van gets cozy like normal...yet if you park and keep the van running you feel the air go cold again....and when You go again..warm again...anY ideas...

Have you added coolant lately or serviced coolant system? Is the coolant level at proper level. Make sure there is not any air in the system (burb the system).

How many miles on vehicle and is the water pump original, if so the blades on the water pump may be eroded away.