I have a 2003 Tracker with two problems. First, the switch for the heat/ac only works on high and off. What should I try first to correct this?

Secondly, the gas gauge does not work.

Any suggestions to correct these two problems would be greatly appreciated. Thanks!

you mean the blower moter only works in hi mode most like the bloewr
moter resister is burned out its located in the p/s air duckt.