windows quit working and cooling/heating out hen engine star

Car has run just fine since we purchased it in 2004. Small problems with the interior lights flickering. Adjusting the switch seems to have resolved the issue. Recently we started having problems with the AC not working (No fan) and the windows will not come down. Also noticed the air bag light comes on. This happens only when the engine is running. AC fan works fine and windows work when ignition is turned on.