This 2003 GMC Envoy came in with the complaint that the a/c will only blow out the defrost and floor. Not through the dash vents. I checked codes and found a code B0263 for a fault with the mode actuator. I first ran into this problem after changing a battery in one of these vehicles last year. Whenever the battery is disconnected the HVAC unit will perform a recalibration of all doors. This causes the door motors to be moved full cycle and the mode door will stick some times. I now hook a jump box to the system before changing the battery in Trailblazers or Envoys to prevent a recalibration from occurring. This way I will not be blamed for a stuck actuator motor.
Anyways to change the actuator motor, first drop the hush panel under the driver’s side of the dash. There are some parts that have to be disconnected from the panel including the turn signal flasher assembly shown in the next picture.
Next, I removed the lower dash knee panel to have a little more room to work.
I had to pull a push pin retainer out at the left side of the duct work in order to remove the driver’s floor vent.
Now, I could finally see the actuator on the side of the heater a/c box.
I removed the actuator and installed the new one. Performed a recalibration with my Tech 2 and put all the panels back in place. A recalibration can be done by disconnecting the battery for at least one minute, reconnect the battery, start the engine and leave the a/c controls alone. I would recommend letting the engine run for at least two minutes, turn the ignition off for at least ten seconds but no more than thirty seconds and then restart the engine so that confirmation of the repair can be done.
I do not recommend connecting the wiring to the actuator until it is installed. They come prepositioned for easier installation.
The notch at the lower edge of the gear is an alignment point. There is a corresponding tab on the door linkage that needs to be lined up with this notch.
To purchase the mode valve actuator, please click here. To see updated information about actuator positions and alignment, please click here.
Awesome!! Ty for the information. I received my actuator today and will be installing it. Updates to come. :0)
It does not matter where the controls are set. With a little bit of experience and a lot of luck, you can sometimes get the old ones working again for a while. Much easier to just install a new actuator though.
Hey Sparky:
I am trying to change my mode actuator and I was wondering if the knobs on the temperature selector need to be in a certain spot when changing out the actuator. I tried to take off the old one and reposition the gears and I did, but it still didn’t work. Is it possible to make the old one work or do I have to get another one?
Ty for your time and efforts on this matter and hope to hear from you soon. Thank you, Adrian
Hi Joe K,
I know you said that you have tried a recalibration several times. I do not know if you have read my article on the subject. If you have fine but if not you should read it over to make sure that no steps were missed or compromised. You will need to copy and paste the following repair post address.
http://www.sparkys-answers.com/2011/08/hvac-actuator-recalibration-procedure.html
If you have a good voltmeter ,along with the ability and will to test, I could refer some test information to you?
I think you will find your answer in the repair post at the following address. You will need to copy and paste it though.
http://www.sparkys-answers.com/2010/02/2006-chevrolet-trailblazer-blower-inop.html