C5 98 Climate control problem

I recently bought a 98. So far I've had the tranny flushed, changed the oil, using mobile 1 synthetic, put new goodyear runflats on it, and had the front end aligned after putting the tires on, and found that Chevy dealers see a vette and bend you over without a kiss. The car runs great, but the climate control doesn't seem to work. The AC works, as well as the heat, but when I turn the dial to change the temp, the digital readout just flickers and stays at the same number. I know that Chevy will rape me when I pull it into the service department, so I'm trying to find out if anyone has had similar problems, and what might have caused them. Other than that, I love the car. Red with black leather and has ghost flames on the hood and sides.
One other thing, the gas gauge sometimes drops to empty when I know it's full, and the LED is burned out for the security system, however the system does work.
Any suggestions would be greatly appreciated.