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.
Sparky, I’d first like to say that you’ven been great at helping me in the past! I’m hoping you’re able to do it again! I have an 04 trailblazer that has had the coil packs changed, maps sensor, coolant sensor, spark plugs and battery all changed. Recently when i turn on the defrosters,a/c,heat when the car is idling it will run really hard. The RPM’s go up and down rather far and it sounds like it wants to shut off. If i drive down the road with any off them on the vehicle will just shut off. I’ve read to clean the throttle body and that has been done. There are 5 codes coming up p0106 (maps sensor) p0136, p2270, p2271 (oxygen sensors) and p0128(coolant sensor) The helpful people at advance auto said the thermostat would need changed and this was the problem. Is there any info you can give me? or anything you’d suggest?? Thanks! 🙂 –jen
Doing a recalibration might help. The actuator and procedure are different for your vehicle. I have not done a post on one of these yet.
I have a 2002 Bravada that just started not blowing air out of the front vents. It does seem to have flow out of the defrost vent, but not very strong. The blower sounds like it is blowing strong when on high but not much flow. We did change out the battery about a month and a half ago. Should I try to unhook the battery and do the recalibration? If a new actuator is needed is the actuator replacement procedure the same for the 2002? Bravada?
No, it is a different part number and slightly different procedure. The gear/cog has to be separated and stays on the vehicle while the actuator is changed. You have to remove the radio and a/c controls to hold the gear/cog in place while the actuator is removed. It may take some force to separate the two pieces.
Here is a link to the part. You will need to copy and paste the address.
http://store.the-electric-connection.com/15-73044-mode-actuator–chevrolet-trailblazer-gmc-envoy-oldsmobile-bravada–2002-p667.aspx
Is the Mode valve actuator part # you listed for the 2003 Envoy the same for a 2002 Envoy? I am having the same problem. I can also here a clicking sound sometimes, when I change the mode.
Thanks