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Ask Randall C Your Own Question
Randall C
Randall C, ASE Master Tech
Category: Chevy
Satisfied Customers: 12803
Experience:  ASE Master, L1, 32 years, Diagnostic / Electrical Specialist
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Air flow won't switch from vent to defrost when I rotate my

Customer Question

Air flow won't switch from vent to defrost when I rotate my control knob on my 2004 chevy Silverado
JA: How long has this been an issue? How many miles are on the car?
Customer: 160,000 , haven't moved the selector since past summer and just found out by trying to defrost the windshield
JA: Are you fixing your Silverado yourself? What have you tried so far?
Customer: Myself and haven't tried anything due to not wanting to spend money on parts I don't need
JA: Anything else you want the mechanic to know before I connect you?
Customer: No
Submitted: 1 month ago.
Category: Chevy
Expert:  Randall C replied 1 month ago.

Hello, I am Randall. Whet size truck do you have an engine size and.. do you have the full auto HVAC or the manual HVAC

Customer: replied 1 month ago.
5.3 liter and HVAC is manual.
Customer: replied 1 month ago.
Chevy Silverado 1500 Z71
Expert:  Randall C replied 1 month ago.

Ok, I am gathering info , back shortly

Expert:  Randall C replied 1 month ago.

Generally when this happens the mode door actuator has failed. It is a small electric motor mounted on the drivers side of the HVAC case, You work from up under drivers side of the dash. Its called the mode door actuator. I have attached a couple files, one showing how to change it and the other is a location picture