Central air conditioner

If the compressor turns off and won?t come back on during a very hot day, the unit may have built up a high "head" pressure and the high-pressure limit switch may have tripped. This is usually located right inside the access panel on the compressor unit. Simply push the button to return it to operation.

If your central air conditioner doesn't go on automatically:

1) Be sure the thermostat is set to "cool" and set below room temperature.

2) A central air conditioner should be on a dedicated 240-volt circuit; check the main electrical panel and any secondary circuit panels for a tripped breaker or blown fuse. If you find the problem here, reset the breaker or replace the fuse.

3) Make sure the furnace power switch is turned on and that the outdoor condenser's power switch, mounted on the outdoor unit, hasn't been shut off. Also be sure the 240-volt disconnect next to the compressor (in a metal box, usually mounted on the house wall) hasn't been shut off.

4) Turn off the power to the air conditioner and check the thermostat.

5) Remove the thermostat's cover and unscrew the wire from the Y terminal.

6) Turn the power back on.

7) Holding the wire by its insulation, touch the bare end to the R terminal and hold it there for about 2 minutes. If the compressor kicks on, the thermostat is faulty; replace it or call an air conditioning technician. If the compressor doesn't go on when you hold the two wires together, turn the power back off and call a service technician.

Both the inside air handler and outside unit would not come on. After disconnecting the thermostat and reconnecting it and setting it on cool both units came back on. Is this an indication of a bad thermostat or is it possible it reset.