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 would start with then recalibration procedure and go from there. I did a post on Aug 12, 2011 about that. The address is below . You will need to copy and paste it though.
http://www.sparkys-answers.com/2011/08/hvac-actuator-recalibration-procedure.html
I had a similar issue from the sounds of this in my 2003 Chevrolet Silverado 2500HD. I found the actuator for it and replaced it. It worked fine for the first 5 minutes and then went back to the same habits of blowing out of the defrosters and the floor. Any suggestions?
Angel
Is the service engine soon light on? If so can you get code numbers? Can you determine if the compressor clutch is engaged during the active fault?
2003 Envoy XL, Intermittent A/C
ice cold sometimes, no cold air others. I changed out the low pressure cycle switch and it did not change anything. The accumulator gets almost hot to touch when it is not working correctly. Any ideas?
The actuator will clear up the vent problem. A proper cleaning of the throttle body will correct the idle issue. The gas issue is very dangerous and the only link to the other two conditions would be if the fuel lines were somehow disturbed or damaged when the battery was replaced. There are fuel lines and fittings within about a foot of the battery. Is that the area where you saw the fuel leaking? Hopefully in a day or so you will love your Envoy again.