Mechanics

HEATER ONLY WORKS AT HIGH RPMS

2000 Pontiac Montana

Heater problem
2000 Pontiac Montana 6 cyl Front Wheel Drive Automatic 170000 miles

At idle the heater blows cold. Go down the road or just raise the rpms and the heater blows warm. Does anyone know what the little pump is for that is in line with the heater hoses and when it should be on?
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Jring94
October 19, 2010.



Post a pic regarding the pump

Check your antifreeze level, sounds like it is low or there is a restriction in the heater core.

If the fluid is low is will not circulate into the heater core until the water pump spins faster from the raised rpm.