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.
Hi Sparky. I talked to the mechanic who said I need a new clutch/compressor. He came to that conclusion based upon seeing that the compressor was not working and that the clutch did not engage. He said he taped on the coil of the clutch and it engaged and the compressor came on. He said he could not buy them separate and that he would have to purchase a clutch with the coil which came with the compressor.
Does any of this make sense?
Janet
Hi Sparky,
In response to your question about the kind of tests to determine that it is the clutch or the compressor, I do not know. I will call the mechanic. Relative to the “hot” air, it seems like it is just not cooling the air rather than the heater being turned on.
Do you know what kind of test was performed to come to this conclusion? Does the air just stop being cold or does it actually turn to heated air, like the heater was turned on?
Hi Sparky,
I am hoping you can help me, although it is a different issue. I have a 2003 Envoy that blows cold air when the AC is first turned on. After about 15 minutes it blows hot air. If the car cools down (or sometimes just turning off the AC for awhile) then it blows cold air again for awhile. My mechanic replaced the 2 AC pressure switches which did not help. He now says I need a new AC compressor clutch or compressor. Does this seem reasonable? As you can imagine it is expensive at about $1000.
Thanks.
Janet
After two years not having ac through upper vents I followed your tutorial and it worked thank you