Blower Motor Switch: October 24, 2017

The HVAC blower switch on my 99 Chevrolet Tahoe was not working in all the positions. Prognosis (hypothesis): blower motor resistor bad.

---

Diagnosis

Upon further inspection, I found that the actual switch and connector had a couple of pins that got too hot and burned up. Of course it begs the question: What caused too much amperage to flow in the circuit and overheat the wiring connectors? Was is from an initial spike when the circuit is switched on or from reduced resistance in a circuit component such as the blower motor itself? So the initial prognosis of a bad blower motor resistor causing a lack of blower fan speeds was incorrect.

Blower Motor Switch Issues:

The image to the left shows a couple of female pins with burn marks. Replacing the switch and connector restored the operation of all blower motor fan speeds. However, further analysis should be performed to ensure the resistance inside the blower motor is within tolerance.

---