from what i heard i need to do a procedure to re calibrate the car computer
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2004 GMC Envoy Question: i am replacing one front and 2 rear door blend actuators what do i need to do.
Alternate Method (w/o Scan Tool)
Clear all DTCs.
Place the ignition switch to the OFF position.
Install the HVAC actuator.
Connect all previously disconnected components.
Remove the HVAC B fuse for a minimum of 10 seconds.
Install the HVAC B fuse.
Start the vehicle.
Wait 40 seconds for the HVAC control module to self-calibrate.
Verify that no DTCs have set as current DTCs.
hope this helps