Under the passenger side of the dash, behind the a/c blower motor. It has a long wire connector attached to it. The GM part # you need is 89018643, and it lists for $38.65 plus tax at most GM dealerships.
Replace the blower motor resistor.
faulty blower motor resistor
There is a removeable panel below the glovebox. It is in front of the blower motor against the firewall. It has a wire connector from the loom and then it plugs into the blower motor
Recommend you check the blower motor resistor.
If you are referring to the blower motor resistor then it is inside mounted on the evaporator case.
Right next to the blower motor
There is only one blower motor resistor and it is located in the evaporator housing.
In a 1988 Chevy 2500, the blower motor resistor can be found on the passenger side. It usually is behind the glove box.
The blower resistor controls the speeds of the blower motor Hi-resistance lower motor speed Lo-resistance higher motor speed
In the truck!
where is resistor pack on 2010 impala lt 6 cylinder 3.5 motor
resistor module is on the right side below the dash next to the heater motor next to the fire wall you will have to remove a kick panel by the glove box