Auto Climate Control Not working properly Hot and cold

[J-ROd_09]

I have an 09 sierra denali, I noticed the problem after I added a factory Nav unit 3 months ago but I am not sure they are related. What is happening is when the auto climate is on and you adjust the temperature control up or down sometimes it defaults to full heat regardless of the temp setting. It would do this immediatly after getting a boost(happened twice) I have since changed the battery as it was toast and maybe it was losing memory or calibration and would reset itself after a while. I have been driving it for about a week now and it seems to do this intermittantly still. It works fine if you start the truck and leave it on the temp setting. But if you change iot up or down it seems to always turn up the heat. You can notice a considerable temperature difference in the air between the drivers and pasengers zone vents. Not sure where the climate contol temp sensors are but maybe I have blocked them by mistake or they are faulty. Just hoping someone can shed some light before I take it in to the stealer.