More than likely the blower motor resistor pack is defective. The fix is to replace it.
There is no need for the fan to run while traveling at highway speed. There is plenty of air flowing through the radiator at high speeds to keep the system cool. The only time it will work at highway speeds is when the A/C is on.
Because it's broken...
fan speed control switch is bad. Replace it as long as the other speeds work fine.
Your heater fan resistor module requires replacment
it could be your fan motor is going to go
If your 2002 GMC Sierra makes a whistling sound that fades away during acceleration, it may mean that your fan belt is not properly attached.
Check the blower motor fuse Check the fan switch
How do you remove the fan shroud on a 2004 get envoy
Removal of the cooling fan on a 2002 GMC Sonoma 4.3l begins with disconnecting the battery, removing the wiring harness to the fan, and taking off the protective shroud. The fan can then be unbolted from the frame and removed.
GMC, or General Motors Corporation is an American company.
Canada
It will if the ac is on.