hey guys, I've had alot of questions about this in that past few weeks, so I decided to just post u[p the Re-Park or Re-Sync Procedure for the AC Motors. If you're having propblems with the air mode or temp modes, in your AC HVAC system, try this before you go to another drastic decision. Usually this corrects the problem without having to see a GM Service facility. If you Moderators are reading, you may want to add this to a Sticky Thread. Anyways...below is the info you seek....lol.

Actuator Recalibration
When replacing the HVAC control module it will be necessary to allow the HVAC control module to perform a calibration process. When installing the HVAC control module be sure to perform the following:

Important: Do not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.

Place the ignition switch to the OFF position.
Disconnect the scan tool.
Install the HVAC control module.
Connect all previously disconnected components.
Start the vehicle.
Wait 40 seconds for the HVAC control module to self-calibrate.
Verify that no DTCs have set as current DTCs.
When replacing the HVAC actuator it will be necessary to allow the HVAC control module to perform a calibration process. When installing the HVAC actuator be sure to perform one of the following:

Important: Do not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.

Preferred Method (w/ Scan Tool)
Clear all DTCs.
Place the ignition switch in the OFF position.
Install the HVAC actuator.
Connect all previously disconnected components.
Start the vehicle.
With the scan tool, initiate the Motor Re-calibration feature of the Heating and Air Conditioning Special Functions menu.
Verify that no DTCs have set as current DTCs.
Important: Do not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.

Alternate Method (w/o Scan Tool)
Clear all DTCs.
Place the ignition switch to the OFF position.
Install the HVAC actuator.
Connect all previously disconnected components.
Remove the HVAC/ECAS fuse for a minimum of 10 seconds.
Install the HVAC/ECAS fuse.
Start the vehicle.
Wait 40 seconds for the HVAC control module to self-calibrate.
Verify that no DTCs have set as current DTCs.

 

 

Is this why only me heater works after a tranny swap?

 

...HMMMM....it's not out of the realm of possibility but...it sounds as if you may have a small electrical problem if it just decided to quit after you replaced the Trans. Try it and see.

 

Sticky this mods!

 

This is definitely sticky material, seems someone has a relevant problem once a week.

 

Hmm, well it fixes itself after a while, like a few start ups or something. But until it does, It will only blow heat. Then it just starts working, After all my tranny swaps it happens. Maybe it just has something to do with disconnecting the battery.

Thanks for posting BTW.

 

Found this on fullsize...in the tech setion for replacing the actuator. (Temp control not working on 99+) <-- for those interested on the how-to. Mods if this is against the rules feel free to edit or delete.

Torque_Wrench, can you or anyone for that matter verify this?
From what you posted, if I'm reading it correctly, those are directions for a relearn/recalibration after installing the new actuator? correct?

Will the procedure posted on fullsize...work?

 

The re-learn/re-calibration is used to reset the actuator drive motors back into the proper drive boundaries. From time to time they forget where to stop and where to start. This is the procedure that I posted up.

I'm sure that the find you posted will work. But ask yourself, why turn the igniton on for 3 minutes? That's the same as people saying to disconnect "both" battery cables and leave them for 5 minutes and everything will reset. I can assure you that once you disconnect the negative side only and then plug it back up, that it's already reset. You don't have to wait 5 minutes and you don't have to disconnect both.

Choose whicever way you want, to recalibrate, it's to each his own. But I for one, trust the Instructions that General Motors supplies us with, before I trust a nifty little way that someone has come up with in their driveway.

 

Same here. That is why I was asking for verification. Thanks again. You've been a tremendous help.