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.
I installed a new actuator but forgot to recal by battery disconnect. It moved to one side and locked up. I took it apart and moved the gears to un-jam it. Will it still work or is it shot?
The trick is to not move the new actuator from the original, as shipped position. If you do not move the cam it is only slightly difficult to do. If you move it it is darn near impossible. If I remember correctly the two closer to the firewall get lined up first and the last one nearer the seats then has to be moved slightly into position.
I have an 04 Silverado with the same issue as the GMC Envoy, No A/C Vent Control. There is a cam with three curved slots and three vent door pins. Can these be mixed up? How do I know which vent pin to alighn with the proper curved slot?
Hi Bill & Amy,
Disconnecting the battery will force it into a recalibration. Unfortunately that is part of the problem. The recalibration tends to stick these actuators and a new actuator will be needed. I have disassembled the actuators before and rotated the gears until I hit a good spot when a part has not been available due to the time of day or day of the week.
I tried the recal by disconnecting the battery, but no sucess. Do the controls have to be set prior to start up or shut down? Is a prof. recal still required? Thanks