Nothing happens. No hum from outside, no air from the vents, no click from the thermostat. Before you call anyone, work through this list — a good share of "my AC is dead" calls turn out to be one of the first four items, and you can check all of them in about five minutes.
1. The thermostat. Make sure it's set to COOL (not OFF, not HEAT) and the setpoint is at least a few degrees below the current room temperature. Then check the batteries — a blank or unresponsive screen is very often just dead batteries. If you have a smart thermostat, confirm it hasn't lost power or dropped into a schedule you forgot about. This is the single most common cause.
2. The breakers. Your system usually has two: one for the indoor air handler or furnace, and one for the outdoor unit. Go to the panel and look carefully — a tripped breaker often sits in a middle position that's easy to miss. To reset it, push it fully OFF first, then back ON. Reset it once. If it trips again, stop and call; a repeatedly tripping breaker means a real electrical fault.
3. The outdoor disconnect. There's a small box mounted on the wall near the outdoor unit containing a pull-out disconnect or fuses. It can get pulled during yard work or other service and simply left out. Make sure it's fully seated. The fuses inside can also blow.
4. The condensate float switch. This one catches a lot of people in our climate, and it's worth knowing about. Your system produces a surprising amount of condensate in Carolina humidity, and a safety switch shuts the whole system down if the drain clogs and the pan fills — deliberately, to keep water from flooding your ceiling or attic. If your drain pan has standing water, that's your answer. Clearing the drain line resets it. (We wrote a full walkthrough on unclogging an AC drain line.)
5. The indoor unit's switch and door. Air handlers and furnaces often have a light-switch-looking service switch nearby that someone may have flipped, and many have a door safety switch that cuts power if the blower access panel isn't fully latched. If someone changed a filter recently, check the panel is properly closed.
If all of that checks out, the cause is likely something that needs a technician: a failed capacitor (extremely common, and often the cheapest real repair), a burned or pitted contactor, a bad control transformer, a tripped high-pressure or low-pressure safety, or a failing compressor. A telltale sign of a bad capacitor is a humming outdoor unit with a fan that won't spin up.
One caution: don't repeatedly reset breakers or force the system to try starting over and over. If something is electrically faulted or the compressor is struggling, repeated start attempts can turn a moderate repair into a much larger one.
Still nothing? Reinhardt Heating and Air diagnoses no-cool calls across Lincoln, Gaston, Mecklenburg, and Catawba counties, 7am to midnight, seven days a week — with up-front pricing before any work starts.