How Do You Restart Your AC After a Power Outage?

Quick answer: Turn the thermostat to Off when the power goes out, and leave it off until power has been steady for a while, which is what electric utilities ask so returning loads don’t trip a second outage. Then check that both AC breakers are on, set the thermostat back to Cool, and give it several minutes. If it still won’t cool, call for service instead of flipping breakers again and again.

Why turn the AC off during a power outage?

To protect the equipment and to help the lights stay on once they come back. Electric utilities warn that when air conditioners and heat pumps are left on, they can overload electric lines as power is restored and cause a second outage. Picture every AC on the street starting at the same second.

Power also tends to flicker on and off during restoration, and each hard stop and restart is tough on a compressor. Unplug sensitive electronics while you’re at it.

How do you restart the AC once the power is back?

Slowly and in order.

• Wait until the power has stayed on for a while. After a big storm, give it longer.
• Check the breaker panel. Most systems have one breaker for the indoor unit and one for the outdoor unit, and a surge can trip either. Reset a tripped breaker once.
• Look at the thermostat. Some reboot, lose Wi-Fi or lose their schedule, and battery models may need fresh batteries.
• Set it to Cool at your usual temperature.
• Give it several minutes. Many systems have a built-in delay before the outdoor unit starts, which protects the compressor. Switching the thermostat off and on to hurry it along just restarts the wait.

Why won’t my AC turn back on after a power outage?

The most common reasons are simple.

• A tripped breaker, or a blown fuse in the disconnect box by the outdoor unit.
• A thermostat that is blank, reset or set to Off.
• The compressor time delay still counting down.
• A failed part, such as a capacitor or control board, damaged when power came back.

If a breaker trips again after one reset, leave it off and call a technician. A breaker that keeps tripping is telling you something, and resetting it repeatedly can make the damage worse.

Can a power surge damage your air conditioner?

Yes. When power returns with a spike, sensitive electronics in the system can take the hit. Signs include an outdoor unit that hums but the fan doesn’t spin, a burning or electrical smell, a thermostat that stays blank with new batteries, or cooling that just never starts. Those need a licensed technician, not more resets. Some homeowners add a surge protector for the HVAC system or the whole panel for this reason.

What’s different about a heat pump or furnace after a winter outage?

The restart steps are the same, but a gas furnace needs electricity for its blower and controls, so it won’t run during an outage either. When power returns to a cold house, a heat pump may lean hard on its electric backup heat to catch up. Raising the thermostat a few degrees at a time can keep that backup heat from doing all the work. Aux heat vs. emergency heat explains those settings, and Can a heat pump keep up with a Texas freeze? covers cold-snap performance.

How do you keep the house comfortable during a summer outage?

Keep blinds closed, especially on west-facing windows, and keep doors shut to hold in the cool air. If a grid emergency is in the forecast, cooling the house a few degrees ahead of time buys you time. If someone in the home handles heat poorly, get them somewhere cool early. If you run a generator, CPSC says to keep it outside, at least 20 feet from the house, with the exhaust pointed away.

Related guides: Aux Heat vs. Emergency Heat: What Your Heat Pump Thermostat Is Telling You, Can a Heat Pump Keep Up With a Texas Freeze? and Why Is My AC Freezing Up or Leaking Water?.

About Gold Eagle Services: This guide comes from the team at Gold Eagle Services, a family-run Austin HVAC, indoor air quality and mold remediation company founded in 2017. We’re licensed (TACLA119235 and RCO1783), insured and bonded, and we serve homes across the greater Austin area.

Need help with this in your home? Learn about our air conditioning repair and installation, or call 512-489-4653 to schedule a visit.

Related Gold Eagle service: Home maintenance plan