My wife's old 97 S320 has a heating and A/C problem, I have replaced the climate control with 3 additional units. Each unit has exhibited varying degrees of operation, they have in most cases switched from heat to cold or the other way around on one or both sides. When we want heat, we have it for a while then we get A/C, sometimes when we need A/C it works for a while then switches over. I really can not believe that I have had 4 defective units. There must be something that works in conjunction with the control, if I am correct what is it, where is it located and how do I get to it?
Thank you for your response!
Steve

 

hi
maybe you have to check the motor who control the heat water which is in right side of the engine need to open and clean the valves