NEED HELP a/c to heat actuator not working right after alterator change.


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Car is 2010 Gmc acadia slt. I had a post earlier about question whether the battery, alternator, or both were bad. Got it all fixed. It ended up being just the alternator. I drove it home, and the next time I went to drive the car in the 95 degree weather. the drivers side 2 left vents were blowing hot. Everything else blew cold. No matter what I changed it stayed hot on the 2 drivers side vents. The mechanic wanted to charge me a diagnostic fee, and like 50 dollars for the actuator. I told him no and just shot off those 2 vents. I came home and searched on the computer about it. There was a write up about resyncing the actuator. It wasnt for an acadia, but it was a gm, and had the digital controls. So i said why not. I wrote down the directions, and it said to turn key on, and set the controls to auto. then turn off the key, and remove the hvac fuse under the hood. Well I couldnt find one under the hood, but found one under the dash on passenger side. Anyways remove that for for 1 minute, and then reinstall, and start the car for 1-2 minutes, and then shut it off for 10-30 seconds, and it should be resynced. I did that and it worked and was blowing ice cold air, and would switch to whatever settings I wanted. Well it last just a couple days and it is blowing hot air again. I tried to do the resync thing again, and it doesnt work. Does anyone know if that is the proper way to resync the actuators in the acadia, or was it just a fluke thing for me, and how do I know if the actuator is just bad? How tough is it to change the one on the drivers side vents? Thanks for any help.


I don't know the Acadia but if the actuators are anything like GMT360's, it could have died as a result of the dead battery and doing a re-calibration on its own after the power came back. This is a very common issue with 360's, so much so that some will try to avoid disconnecting the battery but all that does is delay the inevitable.


Well-Known Member
What brand of actuator did you buy?

Here's how it works for the 360's. Pull the fuse for 1-2 minutes with the vehicle off (or roll the dice and unhook the battery for the same period of time). Put the fuse back in (or reattach the battery) and turn the vehicle on. Do not touch any of the HVAC controls. Within a minute or less the HVAC should run through its own diagnostics/testing.

The HVAC diagnostics/testing lasts for about 1-2 minutes. If you are still feeling warm/hot air then the actuator you bought is bad... It happens to new parts sometimes. Make sure you are buying AC Delco//Bosch/Delphi parts.


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I have a traverse and actually did it a different way. I had taken the old acutator out. Then I had run the car. When the new one came and I installed it, I was going to get it to recalibrate with a scan tool (a professional one, that I have access too as I borrow it from work) but when I started the car with the new one installed, I could here it recalibrating itself without the scan tool. My Mitchell repair instructions said to clear the codes, so I did that as well.


Well-Known Member
I had read a thing online about re-calibrating it....I think they called it re-syncing it...Anyways I turned key on, and set air to auto. Turned car off. removed fuse for 1-2 minutes. Then reinstall fuse, and start car for 1-2 minutes, and then turn the key off for between 10-30 seconds and then it is suppose to reset. It hopefully it is fixed, I dont know what brand it was. I just entered in the part number on ebay, and bought the cheapest one. I hope it last for awhile at least.

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