2001 GMC Sonoma Fan Blower Switch

Old 01-18-07, 07:07 AM
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Join Date: Apr 2001
Location: USA
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Question 2001 GMC Sonoma Fan Blower Switch

Hello Everyone. Yesterday it was colder than it has been here in NJ so far this winter. My Truck had sat for 5 days. I jumped in to go to work threw the switch to defrost and the fan to high {setting 4}. Within seconds I smelled burning electric and did not hear the fan motor. I turned off the defrost as the fan switch does not have an off position {settings 1-4}. I don't usually leave the 4cyl warm up and just take off, but because of the defrost issue I sat for a couple of minutes. I tried the defrost again and I heard the fan motor kick in. I now only have blower action in settings 1-3 with the blower stopping when it is put on the fastest setting {4}. My guess is that I burned up the switch. Please provide your opinions and thoughts and if you agree that it is the switch, please tell me how to get to it to replace it. I am a back yard mechanic and do most of my auto repairs myself. I really just need to know how to get the dash appart. This truck only has 46k on it and I cannot believe that I am experiencing problems already.

Thanks in advance for your thoughts, suggestions and help.

Old 01-24-07, 09:35 AM
Join Date: Jan 2007
Location: Central Indiana
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Best if you have an electrical schematic to troubleshoot your vehicle. Lower speeds drop the blower voltage by passing the blower current through a set of dropping resistors, high speed bypasses the resistors with a relay contact. You can buy a schematic from on-line services, or public libraries sometimes have them. Call around and find a library that has the 'Motor's Electrical Manual' covering your year. My library won't loan it out, so they let us copy pertinent pages free; I have the schematic for each section of my car.
Old 01-27-07, 01:07 PM
Join Date: Jan 2007
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the high speed for the fan is run from a relay 1-3 run through a resistor both are located near the blower motor also check the fuses for the heating system somotimes there is a fuse just fore the high speed. A test light can be used to check and see if you have power and ground to the relay and also through the resistor

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