When any of the climate control selections are on, a musty odor is emitted inot the cabin, espescially when the fan is on. What is the cause, and how may it be corrected. Sometimes my a/c after being on for a while looses its cool, and air turns warm and muggy,and cold air becomes unavialible. What could be the problem here?
And in the winter, when the heater is on, air becomes too hot and cannot be cooled down by lowering the temperature selector. And when this sometimes happens, the hot air wont stop coming into the cabin so I have to resort to opening a window. Whats wrong with my climate control?

The musty odor comes from mold in the air ducts. A result of moisture buildup. Running the heater full blast for a while should help. As for the air getting hot, I had the EXACT same problem. Turned out that the AC compressor was only engaging intermittently. It soon froze up and now needs replacing.