The heater fan stops from time to time and then comes on and/or speeds up when the brakes are applied. It will shut off completely, then spontaneously comes back on and then may speed up when the brakes are used and then slows down to normal speeds - and then will spontaneously shuts off. What is the connection with the brakes? Is there an electrical connection? Is there some physical shifting of the the fan when the brakes are applied?
Heater Fan Blower on 1998 Volvo V70
by jsc in Seattle, WA on November 05, 2009
2 answers 1 comment
ANSWER by munkyrench on November 06, 2009
Do you have automatic or manual type climate system? Are the lights for the A/C control head flashing? This sounds like an issue with the blower power module, it is what controls the fan speed. Most cars use a resistor pack to control the fan speed, this is done electronically. My thought is that the blower power module or the A/C control head is the problem. About the braking connection, these fans are electronically controlled from a blower power module, and that is controlled by the A/C control head. As the vehicle gains speed the blower fan speed is actually reduced slightly by the control module, this is to compensate for the added airflow through the vehicle as the car is moving.
ANSWER by Visitor on September 09, 2010
Mine was doing same thing. The motor is so woren out that it can't start on it's own. I could spin mine by hand and it would start & run. Great detailed video on youtube on replacing it.
COMMENT by me2car on October 12, 2010
youtube? what should I type in couldnt find?