2004 Burb a/c control problem

2004 Suburban with dual manual a/c controls. My problem was first going from a/c all of the sudden it would switch to full heat. I could pull over stop the engine for a minute and restart and it would correct itself. Started doing this a lot so I replaced the mod door on drivers side. It worked for a couple weeks and started same thing again. I put it in the shop and they replaced the other two mod doors and did a lot of wire testing and even talked to Chevy. They were able to correct the air and heat problem but now I have a problem with the air going tothe defrost and floor, maybe a little out of the dash and you no matter what you select it will not move to just floor or dash etc. any ideas would help. The shop cut the cost in half and said they could not figure it out???Thanks,Tom

The passengers motor is on the top of the case, the drivers is on the bottom. These are on the passengers side. The mode control motor is on the side of the case on the drivers side. Look above the gas pedal and toward the passenger side. The motor isn't big (like 4x4" or so) that is the control for where the blow is from....

Tried another mod motor on driver side and still have a problem with controlling where the air comes out. Now the heat came on just on the driver side again. All mod motors have been replaced ??

Does it work int? Sounds like a loose pin in a connector... Have anyone you can swap heads with to check it? The control units are easy to get too.