97 320S Climate Control
 

The heating and A/C in my wife's old car has been acting up. With the original climate control it started to pour heat out of the right side of the car. Then it would shut down the heat and turn the air on. I have changed the climate control a total of 4 times with varying success the current unit works for a while both sides then the system goes into the A/C mode. I am thinking that it is possible to have two controls defective, however to have four defective is a stretch. There must be another componet that is affecting this system, does anyone know what this might be, where it is located and how to access it?
Thank You for your response!
Steve

the pushbutton unit can be programmed using the pushbutton unit itself by pushing various buttons but the problem is probably the usual stuff, low charge, problem with the ac system or problem with the vacuum system for the climate control duct flaps.