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.
You are correct on the procedure. However yours is new enough that you will only need to let it run for one minute. It does not matter where the controls are set prior to removing the fuse or disconnecting the battery.
I am having a similar problem having just replaced my battery in 2004 Envoy XUV. This is the second time replacing the battery and did not have this problem the first time, but now I am only getting air to blow on windshield and floor and not thru dash vents. I plan to attempt the recalibration. After I disconnect the battery for the 1 minute or longer and then reconnect and start the car..should I let it run for 4 minutes (without touching the AC controls), then turn off and restart after 10 seconds?
Also, should the AC controls ( I have dual manual controls) be in any certain position and should the vent (ie dash, floor, dash and floor etc) be in a specific position prior to the recalibration. Sure hope this works and thanks for your help
You really need a scan tool capable of reading HVAC data and bidirectional controls to do accurate testing. There are some tests that can be done with a voltmeter, but it is very difficult to get the leads into position and you would likely need an assistant and a lot of data. You could try a recalibration to see if it may correct the condition. Look at the left side bar for the recalibration link.
Hello Sparky!
My 2004 Oldsmobile Bravada is having the same issues as everyone, no dash vents work but defrost and floor do. Is there any way to test the old actuator before purchasing a new one? I’m questioning if this is the solution to my problem as the battery has not been disconnected recently.
Thanks a bunch! 🙂
Thank you for your help. I will try this.