A/C problems

The air was not cooling the car, so I had the refrigerant checked and it was low and had it filled up three years ago. It was slightly better, but it did not seem to push enough air out of the vents. I started hearing a bapping racket coming from the blower motor area. The blower motor and the burnt resistor were changed out. The air worked better, but right away the knob that turns from vent to defrost became hard to turn, so I only got air on floor and defrost. I figured out this could be manually adjusted. However, I took to someone to repair and they put in an actuator. Nothing was resolved, so I tried to take it to a different shop and they said they did not have time to look at it then (I got an oil change). However, when I started home the knob for cold to hot broke too. Beyond that, air comes out of the vents even when I have it set to 0. The other item is my air was cold, but not cold enough. Since, the air was not running cold enough I had the refrigerant checked at a quick lube, because I thought that maybe the repair on the blower motor area and my use of high ac output during the floor/defrost situation may have used a lot. They said at first it told them it was not in the good area, but they tested it again and it was good on refrigerant. Thanks.