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Don 'Mo Lurch'
Don 'Mo Lurch', Auto Mech / Electronics
Category: Chevy
Satisfied Customers: 20441
Experience:  Chevrolet Cert., Heavy Line Mech, Race Shop Owner, Mobile Electronics.
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2007 Chevy Tahoe: heater and vent selection

Customer Question

2007 Chevy Tahoe heater controls don't work properly. System blows cold air when temperature is set to anything but 90 degrees. (setting it to 90 will blow hot) AUTO setting causes AC to come on & fan speed and vent selection to change erratically as if it's trying to calibrate.
I attempted to recalibrate the actuator by setting the controls to low fan speed, temp to cool, airflow to dash vent and then disconnecting the negative battery lead as suggested in another post. Any assistance will be appreciated... Thanks!
Submitted: 6 years ago.
Category: Chevy
Expert:  Don 'Mo Lurch' replied 6 years ago.


Please try:

Remove the HVAC/ECAS fuse for a minimum of 10 seconds .

Install the HVAC/ECAS fuse.

Start the vehicle.

Wait 40 seconds for the HVAC control module to self-calibrate.


If the System does no Calibrate, then you need to have Dealer Scan Tool check System as it sounds like a Air Door Acuator is not adjusting the Air Door

Customer: replied 6 years ago.

Wouldn't that basically have the same effect as disconnecting the negative battery lead?

If not, I see 2 fuses listed as "Climate Controls (Battery)" and "Climate Controls (Ignition), Would these be the right ones?


Expert:  Don 'Mo Lurch' replied 6 years ago.


No, as disconnecting the Battery does not reset.


Is this Automatic Climate Control or Manual??

Customer: replied 6 years ago.
Ok, it's Automatic with separate Passenger and Aux (Rear) functions.
Expert:  Don 'Mo Lurch' replied 6 years ago.


Should be fuse 38 underhood fuse panel

Don 'Mo Lurch' and 3 other Chevy Specialists are ready to help you
Customer: replied 6 years ago.

Did the trick!

Thanks Lurch... Appreciate the help!

Expert:  Don 'Mo Lurch' replied 6 years ago.


Thanks for using J/A

Customer: replied 6 years ago.

May have spoke too soon... Back to cold & erratic this morning.

Scan tool time?

Expert:  Don 'Mo Lurch' replied 6 years ago.


Sorry to hear that, sounds like one of the Actuators is sticking or the Blend Door is.
Use of Scan Tool will be better than taking Dash apart to look, as that is a pain

Customer: replied 6 years ago.
That's what I figured. Thanks again for your help
Expert:  Don 'Mo Lurch' replied 6 years ago.


Thanks for using J/A

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