My A/C unit won't kick on. I have a mercury dial thermostate. I just changed the filter. I put my dial to 70 and nothing. I had 2# of Freon added to it in 2005. Shouldn't it still be OK?

If it is low on refrigerant this would not keep it from running, check your breakers or fuses, does the fan in the furnace run ?Check to see if the panel door is put back on properly, because there is a safety switch on the door panel.

If you even have a slight leak the freon you had put in would have leaked out.As far as not coming on you need to ceck the breaker box and be sure breaker has not tripped. Also check fuses at the disconnect box next to outside unit. If all OK you need to check and see if the contacto is pulling in at outdoor unit. Check to 2 wires coming out to outdoor unit from inside that they are not broken. Do you hear any noise? Humming or buzzing? Chack the capicator. It should be flat on top. Form thermostat, disconnect the red green and yellow wires, now does it run? Disconnect power first before working with wires in thermostat then turn back on after they are connected. Not bulged. Post back with results.