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 am also having the same issue, except MANY more since I have changed the battery 3 weeks ago!! In addidtion to the exact description of your a/c problem , my 04 envoy has “forgot” how to idle when stopped at lights, or in park and will sometimes die. It ONLY happens when the a/c is on!! Dealer suggested a throttle body clean MIGHT fix the problem…. any suggestions. I am going to buy the a/c module thing and have my husband follow your instructions, but I also have to figure out the RPM idle issue. Also tonight when I started my envoy gas started pouring out everywhere!!! I turned the engine off and the leak stopped , I have to wait to rip the dealer a new one in the morning, seeing that I was there a week ago complaining of the vents, the rpm idiling issue and a gas smell and they told me nothing was wrong with the fuel system and it wasnt dangerous to drive…… I hate GMC 🙁
It does not require physical strength. It does however, require a good bit of flexibility, hand eye coordination, patience and of course a few tools.
Is this something a woman can do I have never fixed a car but I do not have any money to take it to the shop, so i really need to fix it myself. The pictures make it look easy but I need to knoe where I might reun into problems during the install
It has 77000 miles. We are the second owner and I try to fix things on it when I can. Update: the dealer is going to replace the resistor and calibrate the actuators. They hooked up another resistor to the blower and it worked fine. They are still saying that if the blower is faulty, it will fry this resistor as well and then I will ahve to buy one of them as well. I think the resistor job is beyond me. I will post as to the outcome. Repair bill including diagnostic fee: $290.00 Let’s hope it is the fix. Thanks
You may or may not need to blower motor assembly. The blower speed controller has been updated and I just did a post on installation of the new part on a Yukon. The locations are different by a few inches but it is the same part and same repair. There are links to older posts that have testing procedures if you need them. There is a link on where to buy the controller and if you think you need it they can supply a blower motor as well. How many miles on your vehicle?
http://www.sparkys-answers.com/2011/07/2003-gmc-yukon-bower-erratic-not.html