Defogger Controls problems of the 2002 Mitsubishi Galant

Heater no longer works.

I purchased my 2002 Galant in August 05. When I first turned the dial to heat, it made a "clicking" sound and then started blowing warm air. I noticed that every time I turned the heating/cooling dial it made the "clicking" sound. In April 2006, the "clicking" sound quit and so did the heat. I took the car to a mechanic and was told it was the heater core. I purchased a heater core from the nearest Mitsubishi dealer approximately 50 miles away only for the clicking sound to come back once and to find out the heater core is not the problem. The dealer will not take the $200. Part back saying Mitsubishi will not accept it. I have talked to several others that own 2002 Galants who have the same "clicking" sound. Corporate Mitsubishi was not any help in this situation.