My control flap for AC heater controls from face vent to feet vent is messing up

I am having issues with AC blower controls flap will go from face to feet after a few minutes then comes back randomly
I recently found out I had a leak on AC compressor and had it replaced at a shop. I have had issues with my AC button on my AC Heater control switch. I would push the AC switch and start driving down the road then it would would randomly turn off by itself. I looked up online and and seems to be a common issue with several GM's around that year. I saw a video on how to fix on your own (didn't think I would be that crafty) so I just bought a new AC Delco AC Heater control switch. I installed the control switch and for the first time in a long time I had continuous cold AC. But now it seems another issue has popped up. When I get into car and turn on air I always have just regular air going thru the top face vents. I hardly ever use the feet fan even in winter. The AC will be running fine then it seems the face vents go out and only can feel a lower feet vent. This is not permanent as while driving it will switch back to face or after parking. Is this an electrical, vacuum or bad new switch? Is the flap controlled by a vacuum or some type of electrical motor?
Also, we had an unusually cool night and I tried something new I had run the face vent with just warm air and it stayed to face vents the whole trip. So not sure if that will help in anyway but thought I would include it.
My car has 159,268 miles. My car has an automatic transmission. It has the 3.1 L V6 engine.