Before you begin
On digital climate control units for the Chevrolet Trailblazer, it is common for the blower motor resistor to fail. This is due to a design flaw of how the resistor is cooled. Symptoms include climate control blower randomly failing, not being able to select all fan speeds, and complete cessation of blower motor operation. Aftermarket blower motor resistors have a heat sink that improves the cooling capacity of the resistor, and makes it less likely to fail.