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.
had battery replaced same issue removed HVAC fuse # 39 under rear seat waited 1 minute then replaced fuse Turn on ignition do not start engine. Wait 2 minutes then start this will recalibrate the actuators I got this from one of the web sites it worked just fine. All vents work correctly now.
Hi John,
I suspect that all of your problems started with a a battery disconnect. Did you perform a recalibration after replacing the mode actuator? To correct the stalling and surging idle problem the throttle plate will need to be cleaned. Make sure that you do not spray throttle body cleaner into the TB instead it will need to be sprayed onto a rag and then wipe the throttle plate and bore clean. Use gloves to protect your hands.
Sparky, I have the same problem, but my 2004 gmc envoy has only air coming out the main vent. I replaced the actuator and did the steps stated, but sill nothing coming out the floor or defrost vents. After I replaced it, if I change the settings on the vents my idle go’s up and down and it died twice. Also going down the road at night my lights will flicker and my battery gauge will go down and back up. Any info?
Unless you have adjustable pedals in your vehicle it is only a 10 to 30 minute job to replace the actuator. The part (15-73956) is 44.95 at
http://www.the-electric-connection.com
Tried it 4 times and unfortunately it did not fix it so I am assuming the mode actuator is not working. My local independent repair shop who has done about 3 or 4 of these actuator jobs recently for the same thing recommended calling GM to find out if there was any type of recall or campaign. All I got when I called the national GMC customer service was that there is no recall and they will gladly set you up for an appointment at the dealership. Not the answer I was looking for. If there is a next time for me to change the battery on this car, then I will be sure to hook up my black and decker jumpstarter to the terminals to keep power working through the car. Thanks for your help and it was worth a shot.