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 had a stuck actuator on my 02 Envoy, which was caused by disconnecting the battery during replacing the camshaft pos. sensor. After a few days, I bought an actuator but I checked it one more time before initiating the install, and it worked just fine. It has been working fine since then. Any reason why it started working??
Hi Mrs Lucas-Moore,
Sorry the answers got a little out of sequence. It would seem that you have two different issues and neither one is related to an actuator. The radio problem is a power supply problem to the radio or an internal radio issue. The rear blower problem is dependent on the type of system you have. Rear vents at the back of the center console, manual rear a/c or auto rear a/c?
Double check you installation and make sure that the actuators are calibrated.
http://www.sparkys-answers.com/2011/08/hvac-actuator-recalibration-procedure.html
You may also need to replace the defroster actuator to get the full flow back. Did this problem occur after a battery disconnect? I am enclosing a post address below that will help you identify the actuators. You will need to copy and paste the address.
http://www.sparkys-answers.com/2010/12/2004-chevrolet-trailblazer-identifying.html
i replaced the actuator like you said but now the upper vents will not close all other vents work but the floor vents are week?
Hi sparky, I am having a similar problem with my 2003 GMC Envoy SLT. My rear vents and radio are not working. They stopped working about 2 years ago and I think it was after i replaced the battery (can’t really remember). Also the radio makes a loud popping noise like the speakers are bursting and then the front radio dislpays the incorrect time. My front vents work fine with face and leg settings. Do you think the acutator is the problem for my rear vents and radio not working?