With the cold weather arriving I’ve recently noticed that when I have the heater on it does fine while I’m going down the road. However when I idle at an intersection the blower still works but the heat drops off. Any ideas? Sircharles
You have a classic case of air trapped in your cooling system. That or your coolant is low. Check the coolant in your radiator…not the overflow tank.
Good advice–as usual–from missileman.
The only thing I need to add is that the OP should be sure that the engine is stone-cold when he removes the radiator cap to check the level of the coolant.
Otherwise is the engine coolant temp gauge behaving as normal? Stays steady in the range of about 190-210 degrees after warming up?
Google your make, model, year, and engine, plus “water pump vane erosion” and see if anything pops up.
Also ,it could be a vacuum leak, many heater operations are vacuum controlled. We can’t be more speciufic without knowing year, make, model and mileage.