Is the Buick hvac recalibration process the same as the gm truck/suv

ID Status Date Year Make Model Transmission Type A/C Controls Public/Private
#16370 Closed 1999 Buick Century Limited public

Good morning Sparky. This may be a resurrection of an old thread but I have been working on a 1999 Buick Century HVAC unit with automatic controls and dual-zone climate control . I have already replaced the blend actuator doors once I am about to do it a second time. But before I did that I started searching the internet some more and I found a reference to Sparky’s answers from a YouTube video. So I wanted to ask if that procedure for recalibrating a 2000s Chevy truck HVAC can be performed on this 1999 Buick Century successfully. I have been unable to find a definitive answer otherwise.

Thank you so much for all your help already and for what you do


No, it will not work. In fact there is no recalibration procedure listed anywhere in GM Service Information.

Instead we would have to diagnose and repair whatever problem you are having with the system. Can you provide a complete description of the issue you are having?

Thanks you. Darn! The 1st time I went to replace both door blend actuators, the drivers side blew only cold and the passenger side only hot. If I remember correctly.

The floor/mid/defrost all function correctly.

After the actuators were replaced the 1st time, I feel like it worked for a bit. This is my daughter’s car so I do not know when it stopped working….. But it was driver side cold and passenger side hot again.

Some point after that she told me about a buzzing/clicking. so I checked it out and the Driver side actuator was making the noise when the digital temp was below like 85.. When I turned the heat up the clicking stopped. So it was trying to to go somewhere..
I got around to replacing them a 2nd time this last weekend. Once i removed the “old” actuators I could hear broken plastic inside so I popped 1 open and there was a stripped gear. I figure the clicking noise i heard was the the actuators trying to turn, probably past the stop inside. So I thought I would test them before installing them this time. I have discovered that is Not the thing to do. They went past the notches for the operating range. I found a video on Youtube from AC Delco that showed how to bring it back to the middle, so I have done that but Im Not sure if I should install them at this point and see if the system recalibrates itself, at the risk of it stripping out Another pair of the actuators. AC Delco also has a video showing a computerized recalibration with a fancy scan tool….? I will try to attached the videos. They are about 3 min each.

Hope this helps! And Thank You!


After doing some more digging I found out that there is a learn procedure for the control panel as it relates to the actuators. GM does not consider this the same as an actuator recalibration since once it is learned the actuator can be replaced and will function within the limits set by the original actuator. Therefore  the new actuators do not need to be recalibrated to the system.

Here is the rub though. The “learn” process only applies to installing a new control panel. Or as I found in an obscure TSB  #02-01-39-001, if the battery is disconnected the “learned” settings are lost and the control head has to learn the stop limits as if it were new.

So yes, you can perform a “learn” procedure for your vehicle like you do with the trucks as you originally stated. If you want to remove a fuse to start the process, it would be the Radio HVAC fuse. If not you could just disconnect the battery.

Now, for the second rub. The software in the control panel has an acceptable range for travel set in it for each actuator. If during this learn process the actuator moves beyond this range in either direction the system will lock into a default mode and a code may be set. If this happens GM recommends replacing the control panel with a new updated part. Which was expensive and is no longer available. There are some work arounds but I will leave that for a later discussion if needed.

Thanks you for all the info and your time. I plan to do it this weekend.

I think the best sequence of events would be as follows…
Disconnect Neg Terminal before installing the new actuators.

What I would like to know is, should I set the hvac unit to Auto before disconnecting the battery?
And, should I Also pull the fuse while the battery is disconnected?
I understand that, in theory, disconnecting the battery Should cause the system recalibrate/relearn, is pulling the fuse necessary or helpful?
I remember the fuse method is with the battery connected and only for 1 min… So…?
Thank you!


If you plan on disconnecting the battery then there is no need to remove the fuse.

The control panel does not have to be preset before disconnecting the battery.

Some of the more important things to keep in mind is that the learn process can take between 1 and 4 minutes, assuming there are no issues. Do not touch anything during this time. Once enough time has passed and there is  no more actuator movement the ignition will need to be turned off for at least 10 seconds but no longer than 30 seconds. After that, restart the engine and check system operation.

If an actuator over travels and gets stuck, GM recommends replacing the control panel with updated programming. There are some work arounds to this though.


Awesome thank you so much for your replies and info. One last question. Do I just disconnect the negative or the positive or both?


Just the negative.  Leave it disconnected for at least one full minute.


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