Help!

I have a 2002 Dodge Ram 1500 4x4. When the truck is started no heat comes out even after 25 minutes. Heat will start only after driving but will stop if idling again. Anyone have any suggestions so I at least can have some knowledge before going to the garage?

Thanks

Could be a bad heater control valve or a heater control cable that needs adjusting.

It could also be a thermostat that is stuck in the open position. Also check your coolant level.on some vehicles if there is not enough coolant in the system in won't reach through the heater core and I f coolant is that low then you will have bigger problems than just "no heat at idle"note I said on some systems as I do not know exactly how yours is set up