What to Do When Your AC Stops Working

Step 1: Check the thermostat

• Is the display on? If not, try fresh batteries.
• Is it set to COOL, with the setpoint at least three degrees below room temperature?
• Is the fan set to AUTO rather than ON?
• Did a schedule or a vacation mode take over?

Step 2: Check the filter

Pull the accessible return filter. If it is grey and matted, replace it. This single item causes a surprising share of no-cooling and frozen-coil calls in this climate, especially during heavy summer runtime.

Step 3: Look for ice

Check the copper lines at the outdoor unit and the indoor coil area. Any ice means you should switch cooling off, set the fan to ON, and let it thaw for several hours before doing anything else. Running a frozen system risks compressor damage.

Step 4: Check power

• Look at the breaker panel for both the air handler and the condenser.
• Reset a tripped breaker once — firmly off, then on.
• If it trips again, leave it off and get help.
• Confirm the air handler service panel is fully closed so the door switch engages.

Step 5: Look at the drain pan

Standing water in the pan usually means a clogged condensate line, and most systems will refuse to run until the float switch resets. That is a specific, easily described problem when you call.

Step 6: Watch the outdoor unit

With the thermostat calling for cooling, go outside. Is the fan spinning? Do you hear the compressor? A hum with no motion is a very different fault than complete silence, and reporting which one you observed helps.

What not to do

• Do not open the electrical compartment on the condenser or air handler.
• Do not attempt to add refrigerant.
• Do not bypass a float switch, door switch or disconnect.
• Do not repeatedly reset a breaker that keeps tripping.
• Do not chip ice off a coil.

Staying comfortable while you wait

Close blinds on sun-facing windows, run fans, avoid the oven and dryer, and stay hydrated. If indoor temperatures climb into an unsafe range — particularly with infants, older adults or anyone heat-sensitive at home — relocate rather than waiting it out.