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Juan Crespo
Juan Crespo, ASE Certified Technician
Category: Chevy
Satisfied Customers: 1526
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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I have a 2003 chevy s10 and the heater controls won't change

Customer Question

I have a 2003 chevy s10 and the heater controls won't change modes they are stuck in the by level position
JA: Have you checked the coolant level? Has there been any leaking from the hoses?
Customer: the modes will not change , defrost , floor , by level they are stuck in the by level position
JA: Are you fixing your S10 yourself? What have you tried so far?
Customer: yes I'm doing it , I understand they are vaccum operated and have vaccum to the switch
JA: Anything else you want the mechanic to know before I connect you?
Customer: could use a vaccum schematic for this vehicle
Submitted: 9 months ago.
Category: Chevy
Expert:  Juan Crespo replied 9 months ago.

Hi there.

Can you tell us what size engine and drive type are on that S10?

Expert:  Juan Crespo replied 9 months ago.

OK. I took a chance and uploaded the vacuum diagram for a 2003 S10 with the 4.3 V6 and 4WD (see attached graphic). Please let me know if yours is different.

Going by the symptoms you describe and knowing that the default air delivery position is Defrost, I would say the issue you're having is due to a bad mode switch in the control head/module - switch is integrated and not serviced separately.

Please let me know if you have any questions.

Best Regards.

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