Chevy Venture
Heater Cores and Blower Fans
Grand Prix GT

Why does heater fan only work on high speed?

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Wiki User
July 14, 2015 4:46PM

Defective ballast resistor pack.


It sounds like it could be the blower motor relay / resistor. I replaced mine today in my 2001 Chevy Impala. It was next to impossible since I heard that the way to get to the resistor was to remove the blower motor housing and repair it that way. I instead removed the blower motor and got to it that way. The two screws in the back are knuckle busters. Good luck and I hope you have patience or enough money to have someone else repair it.