My AC Won't Turn On, And I Thought The Problem Was With The Thermostat. I Changed The Batteries - Nothing. I Replaced The Programmable Thermostat - Nothing. The FAN Won't Even Turn On When The "Fan-on" Switch Is On. Help?

If the fan is in the "on" position, nothing will work except the fan to circulate air. The fan switch should be in the "auto" position and the heat/off/cool switch should be on "cool" position. The temp. Should be set at about 72 unless you want to hang beef in the house then you can set it to 68. Check the fuse in the pc board(purple 3 amp). Make sure the emergency switch is on. Check the breakers. Lose the crappy programmable tstat. Those are junk and always cause problems. You really don't save anything with them you actually spend more.