This listing is for a NEW a/c blower resistor (Replaces GM Part #336403) for all Square Body 1973-1987 Truck & 1973-91 SUV with factory air conditioning.
This is the part that mounts on the right-hand evaporator case half mounted on the passenger side of the firewall in the engine compartment. It helps regulate lower blower speeds on the front air-conditioning. ***

*** This will not serve as a resistor for the rear air-conditioning unit on SUV's that installs on the inboard (engine side) evaporator case half on rear a/c systems.

TECH NOTE - The most common cause of failure of a blower resistor is a failed or failing blower motor.  Failure to correct this problem will burn out the coils and voide warranty of the switch.  This part does not control your high-fan speed.  If you do not have a high-fan speed, the high-fan relay and/or fan blower switch is the likely problem.