Jeep Grand Cherokee Heater problem

My 2011 Jeep only blows hot air on the drivers side vents. When I try to lower the temperature the scale on the dash goes from high to Low, but the air temp stays hot. The year before this also happened on the right side. At that time I noticed bits of black broken plastic on the passengers front floor. Turns out the drive gear on the blend door actuator had worn out. In less than 2 hours I replaced it and it was back to normal. However the drivers side is a LOT more difficult because of the cramped location. I was not so lucky on this side as the blend door was stuck in the closed position. The driven gear on the door would not move freely and the door was jammed closed. Being VERY careful I used a flat blade screwdriver as a lever against one of the plastic teeth on the door shaft teeth and preyed it open. It now moves freely. I only drive it in the winter and when I shut the Jeep off the temp control is always left in the high position. This probably didn't help, so I am from now on only turn the heat up to about 28 instead of 30. That way the blend door may not get stuck so easy. If this helps anyone please subscribe THANKS