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Re: passenger blend door actuator repair
« Reply #10 on: April 03, 2015, 11:41:30 PM »
I've had two recent issues with my 2010 Acadia blend door actuators and I thought I'd share what I've learned.
Issue #1: Last fall, the mode actuator for the defrost/dash/floor selector stopped working. Mine got stuck on the dash mode, but I assume it could get stuck on any of the modes. We didn't notice it until we found that the defrost wouldn't work when the cold weather set in. After spending 2-3 hours swapping the passenger heat/cool actuator with the mode actuator, I realized that both of these actuators were functioning correctly. Turns out that all I needed to do was to pull the fuse and reset the HVAC. This took only 15 minutes. The fuse for HVAC is located under the glove box against the wheel well. The HVAC fuse on mine is on the row closest to the wheel well. On mine it's the blue 15, between another blue 15 and a yellow 20. After pulling the fuse waiting 1 minute and reinserting it, the system reset and functioned normally. Warning: I needed to use curved needle nosed pliers to pull the fuse due to its position by the wheel well.
Issue #2: Today, my wife complained that her passenger side was constantly blowing hot air while the drivers side worked normally. I first pulled the fuse hoping for a quick fix but no luck. By looking at the two actuators under the glove box I could see that the passenger heat/cool actuator was not turning as I changed the setting. After removing the actuator and opening it, I could see the burnt area on the circuit board around one of the resistors, which I'm pretty certain is the problem.
How the blend door actuators work
Here's my explanation (as best as I can tell) how the actuators function together and it's actually pretty simple and logical:
There are three actuators: one on the driver's and two on the passenger's side. I'll call them 1.) the driver's heat/cool, 2.) the passenger's heat/cool, and 3.) the defroster/dash/floor. The 2 heat/cool actuators move the blend doors to mix hot and cool air depending on what temperature is called for by the driver or passenger. If the passenger side is turned off, the driver's side setting will (under normal operation) operate both actuators. The defroster/dash/floor actuator has multiple settings for the various combinations requested: dash only, dash and floor, floor and defrost, defrost only, etc.
Location of actuators:
All three actuators are identical so you can swap them if needed. For the 2010 GMC Acadia do a search for part number T3983001 to see what they look like. I believe these are used on all Enclave, Traverse, Outlook, and Acadia for 2008 to 2012. The driver's heat/cool actuator is under the ignition switch and the easiest (relatively speaking) to get to. The other two actuators for the passenger heat/cool and the defrost/dash/floor are under/beside the glove box. The passenger heat/cool actuator is the lowest one and the mode actuator for defroster/dash/floor is the higher one closer to the firewall. Both are a nightmare to get to. You don't have to remove the glove box, but it's easier to see what you are looking at if you do. However, even with the glove box removed you need T20 torx bit and an extremely short and or flexible tool to reach the screw heads. All this while you are upside down. Have fun swearing!
Diagnosing and Other Hints
If you are getting cold air instead of hot, or hot air instead of cold, the driver's or passenger's actuator is possibly stuck/broken in the wrong position. Start your search on the side that is operating incorrectly. If the HVAC is stuck in one mode, get access to the top higher actuator on the passenger side (see location above) to see if it is functioning correctly. But remember to reset the fuse first (also above) and see if that does the trick.
Diagnosing a faulty actuator is pretty easy. Again, the driver's actuator and the lower actuator on the passenger side control heat/cool only to the drive and passenger respectively. The higher actuator on the passenger side controls the defrost/dash/floor settings. Once you can see the actuators, simply change the heat/cool or defrost/dash/floor settings to see which one is working and which is not. Each actuator has a 7/16 diameter metal ring with two notches that rotate when it is operating correctly as it moves the blend doors.
In my opinion, the defrost/dash/floor actuator is the most important of the three because it has the most settings and you can set blend doors of the other two manually. So if your defrost/dash/floor actuator dies, I would recommend replacing it with the passenger actuator while you are waiting for the replacement part. Once the driver and passenger heat/cool actuators are removed, you can spin the exposed white knobs which move the blend doors to cold or hot depending on the season. I turned mine from the hot to the cold setting today to temporarily solve Issue #2 above, but it should also work for the driver's side.
Once the new actuator is in place, you may need to pull the fuse (see above) to reset the system. I'm just guessing on the this one, but because the position of the new actuator may not match the current setting on the HVAC, they could be out of sync.
Hope this helps someone.$500.00-$800.00 for the dealer to do this!!!
copy and paste this link with pictures>
http://www.enclaveforum.net/index.php?topic=23505.0
