Quick answer: If your AC will not turn on, check the thermostat settings and batteries, the AC breakers in the panel (there are often separate breakers for the indoor and outdoor units), and the outdoor disconnect switch near the condenser. If a breaker trips again after resetting, stop and call for service. Repeated tripping, burning smells, or buzzing from the outdoor unit can indicate an electrical or equipment problem.
In a Charleston summer, a non-working AC is urgent. Some causes are quick to check safely, while others need an HVAC technician, an electrician, or both.
Safe checks you can do
- Thermostat: Confirm it is set to cool, the setpoint is below room temperature, and the batteries are fresh.
- Breakers: Look for tripped breakers labeled for the AC, air handler, furnace, or heat pump. Reset once by switching fully OFF, then ON.
- Outdoor disconnect: The disconnect box near the outdoor unit should be in the ON position. Someone may have pulled it during maintenance.
- Indoor switch: Many air handlers have a service switch that looks like a light switch near the unit.
- Condensate safety switch: A full condensate pan or clogged drain line can shut the system off.
When it's an electrical problem
Call an electrician if:
- The AC breaker trips immediately or repeatedly
- The outdoor disconnect or its whip is corroded, damaged, or scorched
- Wiring at the outdoor unit was damaged by storms, mowers, or animals
- Lights dim heavily when the AC starts
- The panel is warm or buzzing
Coastal outdoor disconnects corrode quickly. See salt air and electrical equipment.
When it's an HVAC equipment problem
Failed capacitors, contactors, motors, and refrigerant issues are HVAC equipment repairs. If the breakers and disconnect are fine and the unit still will not run, an HVAC technician is the right call. Some problems involve both trades.
Do not do this
- Do not keep resetting a breaker that keeps tripping.
- Do not open the outdoor unit or touch internal components. Capacitors can hold a dangerous charge.
Frequently asked questions
Why does my AC breaker keep tripping?
Repeated tripping can be caused by a failing component in the AC unit, a short in the wiring, or a problem with the breaker. Leave it off and have it diagnosed.
Where is the AC disconnect?
It is usually a small box mounted on the wall near the outdoor condenser. It allows the unit to be shut off for service.
Should I call an electrician or an HVAC company?
If the issue involves breakers, wiring, the disconnect, or the panel, call an electrician. If power reaches the unit but it does not run correctly, call an HVAC technician.
Can storms affect my air conditioner's electrical system?
Yes. Surges can damage control boards and components, and flooding or wind can damage outdoor wiring. Whole-home surge protection helps protect HVAC equipment.
Copperhead Electrical serves homeowners across Charleston, Mount Pleasant, West Ashley, James Island, Johns Island, Daniel Island, North Charleston, and Summerville. Call 854-444-6516 or request service online.