Why does my Ford Windstar blow hot air when driving and cold air when parked or idling?

Answer 1

Two possibilities

• Engine coolant levels are low
• Water pump - impeller can wear down or come loose from the shaft
  

Add coolant to the reservoir on the left side of the engine compartment (reference Owners Manual for more detail.)

Might be a good opportunity to think about getting the system flushed and coolant replaced...

See "Related Questions" below for more, including coverage of the water pump



o. You need to check the level of anti-freeze on your radiator. Mine was low and not allowing fluid to flow through the heater core.

-Thank you, yes, I had the radiator flushed, and it is working better now.

Check your coolant level is topped off in overflow container. had same problem ,temp gauge is ok because the coolant wasn't reaching the heater core, but the engine is being cooled at the thermostat portion of the engine

This is the classic not-enough-anti-freeze situation.

The higher engine rpms when moving is able to push the low level of coolant around - but idling just can't.

Top off the coolant reservoir in the engine compartment and all should be good.

Checking and filling engine coolant is well detailed and illustrated in the Owners Manual.

There is a slight possibility the water pump is failing - the fin or impeller could be wearing away.

See "Related Questions" below for more