Chrysler Repair: Chrysler Town & Country heating system, roland roland, coolant system

Question
2000 Chrylser Town & Country Heater blows cold air. teamperature gauge normal, 1/2 between low and high. I think I am hearing the wind of the electronic motor for the air door when I slide the temp lever from hot to cold and back. The air comes out hotter if the engine is revved. But at idle or normal drive rpm air is cold.
Is there something I can check/repair before taking to dealer? I see that 2000 is just outside of your normal expertise but I am hoping systems are similar. any help would be appreciated.
Thanks Jim

Answer
Hi Jim,
A couple of possibilities: first feel the radiator and see if it really seems to be at around 200F which would be consistent with the gauge reading. It might be that the gauge is optomistic and you really have a thermostat that is opening at too low a temp. Second, locate the two hoses between the engine and the firewall that carry the coolant to the heater core. Compare the temperature feel of the two hoses after bringing the engine up to temp and running the heater system long enough for it to stabilize. If the return hose feel significantly cooler than the output hose it may be that there is an air bubble in the heater core or a clogging of the core that if remediated will improve the circulation of coolant thru the core.
If you recently drained and refilled the coolant system you may have trapped air in the core by not first having turned 'on' the heater to heat setting with the engine running. Then shut it off and drain the coolant (collect for reuse) in a specific manner: you didn't mention which engine you have so let me know because there are a vent or a sensor (depending upon which engine) that needs to be removed while draining/refilling to allow air to escape from the system and thus avoid an air bubble in the heater core.
Roland
Roland