Chevrolet Express 3500 rear heater only operates on high due to failed resistor block on Chevrolet Express 3500

Some Chevrolet Express 3500 owners report experiencing issues with the rear heater only operating on high, which is likely due to a failed blower motor resistor block. This component is crucial for controlling the speed of the blower motor, and its failure can prevent the adjustment of fan speed. Owners may find that the heater becomes stuck on the high setting, necessitating the replacement of the blower motor resistor block to restore proper functionality and allow the rear heater to operate at varying speeds.