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Gary, GMC Technician
Category: GM
Satisfied Customers: 17019
Experience:  15 years gm master tech/15 years ASE master tech
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GM sierra: My 2003 sierra (4.8 liter) heater was stuck on full

Customer Question

My 2003 sierra (4.8 liter) heater was stuck on full blast heat with no control, but after shutting it off it seems to work fine. Do you think this will happen again?
Submitted: 2 years ago.
Category: GM
Expert:  Gary replied 2 years ago.
Welcome! My name is ***** ***** I will do my best to assist you with this problem.
I am sorry for the long wait
when it was stuck full blast heat was it set to cold and just had hot air or the blower motor was stuck on high speed ?
is this a duel heater a/c system ?
Customer: replied 2 years ago.
duel heater; has passenger and driver side controls. The fan works right, but the temperature wouldn't adjust. After turning off the engine, the heater and AC work normally.
Expert:  Gary replied 2 years ago.
which temp acts up ? both ?
Customer: replied 2 years ago.
Just the driver's side, the passenger side worked good.
Expert:  Gary replied 2 years ago.
ok thank you for that information
99 % of these when its just one side is just the actuator that is bad loosing its memory
the drivers temp actuator is located directly under the heat box inside the truck
cut and paste this link for the picture of it # ***** in the picture is the drivers side temp actuator
replacing that drivers temp actuator should correct this problem so it will not happen again!871&authkey=!AP_EWLMpOHq63ng&v=3&ithint=photo%2cgif