I recently changed my instrument cluster with a new cluster that was already programmed. I disconnected the battery to avoid any power surges and when I hooked the battery back up my ac quit blowing out of the front vents it would only blow out of the defrost vents. The odometer was programmed with the current mileage of 107250 but it will go back to 107249 and then back to 107250 while driving. I have tried disconnecting the battery and letting it sit to reset the system about 3 times since and have pulled both the ecm and hvac fuses but nothing has fixed these issues.
same question as here
https://carkiller.com/scottykilmer/qa/99-buick-defrost-and-floor/
I don't think it has anything to do with your cluster, battery, computer or fuses.
I would check the main computer itself (PCM).
