Heater fan only works on high on my 2002 Avalanche

• engine dead?
• car can not drive.?
• battery dead
• fuse blown
• starter dead
• jumper cable starts work?

Does the vehicle start an run ? Check engine light on , codes are stored , hook up scan tool an check codes . GM had issues with instrument cluster gauges not working - new instrument cluster . Does everything else on the vehicle work - headlamps , heater / A/C blower motor etc....

There is a resistor in the fan circuit to give you different speeds and it burns out. It's down by the fan on most cars.

You need to replace fan speed sensor ,located beside the fan under right side of dash

There is a resister in the air duct that controls the speeds...it is where I would look first.

Hello,
You may want to try your fan on all speeds. If it will work on high, you have a bad resistor for the fan motor. ( high speed doesn't go through the resistor ).
If it doesn't work on any speed, I would check the following;
1. Make sure the fuse isn't blown for the fan blower motor.
2. Check, or have checked the wires between the fan control switch and the fan blower motor.
3. Have the fan control switch checked.
4. Have the fan blower motor checked.

I hope this helps you.

You may want to have your fan clutch checked. If the fan on your water pump does not spin very hard when the vehicle is idleing than it doesn't draw air through the condenser and that air keeps the condenser cooler plus it keeps the pressure down on the high side of the ac system. leave comment.

Motor switch has gone out, most likely due to high load on level 5. Replace switch and I suggest lubricating blower motor bearing to help take the strain on the system.

bring to a repair garage

needs blower control module