2003 Suzuki XL7 Temperture control for heating/cooling

I purchased the XL7 new back in 2003, and since the beginning, the temp. Control for the heating and A/C never worked as it should. I took it to the dealer on several occasions and was told it was working fine. (It may have been at the time because It was an intermittent problem, but then on the way home it would start to act up). The temp control knob has the settings "65-75-85" and at 65 and 85 there is a small click at each end of the spectrum. In the summer heat, If you had it set at the far left(65) and it was too cold, you clicked it just past the first click, still showing "65" and it immediately became warm. There was little difference between lets say just past that click at 65 to 75, so you were either cold or hot. In the winter time, you would set it for 85 until the engine got warm, and when you wanted to turn it back because it was now too hot, it would still stay way too warm unless you put it past the last click at the 65 setting and then it would be cold. 85 percent of the time, just one click just past 65 was still feeling like 80. Sometimes it would adjust to be comfortable, but most of the time you had to just constantly flip past that click and deal with one extreme to the other. I put up with it for ten years now. Recently, now in the cold it is set at "85" and it gets warm and then just becomes cold without touching anything, or will not get hot at all until I fiddle with the knob several times. If I move the knob back and forth sometimes it starts to get warm right away and sometimes it takes a few minutes of switching the knob around. I've wanted to attempt to make a repair myself since I'm not made of money, and was going to replace the entire three knob control panel in the dash with a used one thinking maybe it would solve the problem? But I can't find any diagrams of the system online to see if there are other moving valves or switches that may be getting stuck, or some type of relay or something that isn't working properly. The guy I work with used to work on Fords and he said he had to replace many of the moving valves or whatever they call the actual valve that changes the air flow because they would stick. I just can't find anything to show what parts could need replaced and any part numbers and prices to go along with it. I located an entire repair manual online, but it appears to be for a 2002 and earlier which had the manual controls for the temp. Control. Mine is the first year with the electronic, if that's what you call it. Any help would be appreciated. Thanks for you time.