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Amedee, GMC Technician
Category: GMC
Satisfied Customers: 26627
Experience:  ASE Technician advanced level specialist
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The blower will not run. I checked all related fuses and all

Customer Question

The blower will not run. I checked all related fuses and all are ok. When I turn the knob to high I hear and feel the relay enable. I did some reading and learned that the highest setting bypasses the resistor block. Do I have a bad resistor block or a bad motor?
JA: How many miles are on the car? Has the car been starting normally?
Customer: Yes. 180k.
JA: What is the model/year of your GMC?
Customer: 2008 envoy
JA: Are you fixing your Envoy yourself? What have you tried so far?
Customer: Yes. I have ohmed out the selector switch yet. I took the cover off to get to the blower module. That is about as far as I got. Today.
JA: Anything else you want the mechanic to know before I connect you?
Customer: I need to correct my typing. I have not ohmed out the resistor block.
Submitted: 1 month ago.
Category: GMC
Expert:  Amedee replied 1 month ago.

Hello and welcome!

My name isCustomerand I can assist you with your question.

Expert:  Amedee replied 1 month ago.

I am very sorry your having this issue with your vehicle.

I will try my best to answer all of your questions.

However, before we get started, please let me mention a few things.

1. If at any point you would like to speak on the phone, please feel free to request a phone call on your end and I can call you right away.

2. If you dont understand any technical terms or anything that I mention (component tests or theory or operation), please let me know and I will provide you with a more in debt explanation or answer.

3. Please understand that I am here to help.

Have you checked the wiring and signal to the blower motor?

What size engine do you have?

Customer: replied 1 month ago.
Have I checked the wiring and signal to the blower?
Wiring is OK.
I have not checked the voltage to the blower motor itself yet.
What size engine do you have?
4.6L Its the one with the inline 6.I am pretty sure it is the resistor bank. The 4th speed on the blower switch setting went out a two years ago.
What voltages should I be reading for the various speed setting. I presume the highest setting would be 12VDC to the blower motor.
Expert:  Amedee replied 1 month ago.


If the resistor went bad, the blower motor should still work on high speed.

Expert:  Amedee replied 1 month ago.

YES, that is correct. On high speed, the blower motor should receive full battery voltage.