Random AC control issue, 09 Silverado

[2015 High Miler]

I have an 09 SIlverado that has had random ac problems. Every now and then it will blow hot on one side cold on the other, blow only on the floor or will only blow heat, but just on one side but not the same side. Last time was about 3-4 months ago and all I did to fix it was disconnect the battery and wait then reconnect and it worked again until today. It started blowing heat on the floor just on the drivers side. I have had the ac controls replaced after about 25,000 miles under warranty but now I have 130,000 on it and no warranty. This is the 4 or 5th time since Ive had it that its done this. Im wanting to sell it but I need to fix this before hand for the least amount out of pocket.

 

Thanks in advance.