The climate control temperature knob just stopped working. I thought I felt it bind momentarily then start moving freeling again. After that though the temperature control did not seem to work right at all. I could at first adjust the knob somewhat and get heat out of it. Now it is very difficult to get the temperature knob to respond at all. Could it be the Rheostat that controls the temperature selection. Also have been getting a musty smell in the car recently. I have never changed the cabin filter in the car could that be the problem? Also how do you change the cabin filter? thanks in advance for any help you can give. David