Why Is My AC Not Working?
If your AC has stopped working entirely, check three things first: your thermostat (make sure it is set to COOL and has power), your circuit breakers (both the indoor and outdoor breakers), and the safety float switch (if the condensate pan is full, a safety switch shuts the system down). These three checks fix the problem in about 50% of no-AC situations.
THE DETAILS
Dead thermostat. If the screen is blank, replace the batteries. If it is hardwired, check the breaker that powers it. A dead thermostat means the AC never gets the signal to turn on.
Tripped breaker. Check both the indoor air handler breaker and the outdoor condenser breaker. Flip them fully off, wait 30 seconds, then flip them back on.
Safety float switch. Many AC systems have a safety switch in the condensate drain pan. If the drain clogs and the pan fills with water, the switch shuts the system off to prevent water damage. Clear the drain line to fix this.
Blown fuse in the disconnect box. The outdoor disconnect box (near the condenser) contains fuses. If one blows, the outdoor unit will not run. A tech can replace these quickly.
Failed capacitor. The capacitor gives the compressor and fan motors a boost to start. When it fails, you may hear a humming or clicking from the outdoor unit but it will not start. This is one of the most common AC repairs.
🔧 WHEN TO CALL A PRO
If the thermostat, breakers, and safety switch are all fine and the AC still will not turn on, call a pro. A failed capacitor, contactor, or compressor requires professional diagnosis and parts.