Important Notice
This article is general safety information, not a professional assessment of your equipment. Stay away from downed power lines and standing water near electrical equipment. If you smell gas or burning, or a carbon monoxide alarm sounds, leave the house and call 911.
Is it safe to turn my AC back on after a storm power outage?
Not right away. FEMA advises turning off or disconnecting air conditioners during an outage, because power can return with surges that damage motors. When power is steady, check that the outdoor unit and air handler were not underwater or hit by debris. If either got wet with floodwater, leave the AC off until a licensed technician checks it.
| Situation | What to do | Source |
|---|---|---|
| Power is out | Set the thermostat to off and switch off the AC breaker | FEMA / Ready.gov |
| Power just came back | Wait until it is steady before turning the AC on | FEMA / Ready.gov |
| Outdoor unit or air handler was underwater | Do not turn it on; have it evaluated first | ESFI |
| Duct insulation or fiberglass ducts got wet | Plan to replace, not clean | EPA |
| Running a portable generator | Outdoors only, at least 20 feet from doors, windows, and vents | FEMA |
| Water-damaged materials in the house | Dry them within 24 to 48 hours to limit mold growth | EPA |
What should you do with the AC while the power is out?
Turn it off at the thermostat and at the breaker. FEMA's power outage guidance names air conditioners among the equipment to switch off, because power can come back with brief surges or spikes that damage motors.
Switching off at both points means the system will not try to start the moment power returns. That gives you time to look at it first.
If a storm is on the way, do this before the power goes out. If your home has an outdoor disconnect, the small box on the wall next to the outdoor unit, switch it off too.
How do you check the outdoor unit?
Look at it before you touch anything. If there is still standing water around it, or a downed line nearby, stay away and call the utility.
- Look for a water line. Mud, debris, or a dirty ring on the cabinet shows how high the water came. Any sign that water reached the electrical parts means the unit stays off.
- Check for debris. Branches, roof shingles, and trash pressed against the coil or inside the fan guard block airflow. Clear what you can by hand with the power off.
- Check the position. A unit pushed off its pad, tilted, or knocked over can strain or break the refrigerant lines.
- Check the lines. Look at the two copper lines running into the house. Kinks, cuts, or oily spots near joints can mean a refrigerant leak.
- Check the fins. Some bent fins are normal after a storm. Large flattened areas reduce airflow and should be combed or repaired.
If any of these look wrong, do not turn the AC on. Take photos for your records and call a licensed AC contractor.
How do you check the air handler and ducts inside?
The air handler is the indoor part of the system, usually in a closet, garage, or attic. Look for water on the floor around it, a full or overflowing drain pan, and wet insulation on the cabinet or nearby ducts.
Roof damage can let rain into an attic where the air handler and ducts sit. Check ceilings below the attic for new stains. Wet ceilings often mean wet duct insulation above them.
EPA says that wet or moldy duct insulation, or fiberglass duct material, cannot be effectively cleaned and should be removed and replaced. EPA also says moisture should not be present in ducts, and that controlling moisture is the most effective way to prevent mold growth in them.
What if the AC was underwater?
Leave it off. The Electrical Safety Foundation International (ESFI) warns that restoring power to water-damaged electrical equipment without a proper evaluation can cause fire, shock, electrocution, or more damage. Drying it out is not enough, because silt and contaminants in floodwater stay inside.
Have it evaluated by qualified professionals: a licensed electrician for the wiring and disconnect, and a licensed AC contractor for the equipment.
In Florida, work that opens up the system is licensed contractor work. Ask for a license number and check it with the state before anyone starts.
How do you turn the AC back on safely?
Once the outdoor unit and air handler pass your visual check and the power has been steady, restart in order.
- Make sure the thermostat is set to off.
- Turn the AC breaker on at the main panel, then the outdoor disconnect if you switched it off.
- Replace the air filter if it got wet or very dusty.
- Set the thermostat to cool, a few degrees below room temperature.
- Wait. Many systems have a short built-in delay before the outdoor unit starts.
- Listen and smell. Grinding, banging, buzzing without the fan turning, or a burning smell means switch off at the thermostat and the breaker right away.
- Feel the vents after 10 to 15 minutes. The air should be noticeably cooler than the room.
- Check the drain line outlet or the drain pan after an hour. Water should drain, not pool.
If the breaker trips, do not keep resetting it. A breaker that trips again is a sign of an electrical fault, and repeated resets can make it worse.
Can you run the AC on a portable generator?
Only if the setup was designed for it, and never indoors. FEMA says to run generators outdoors and at least 20 feet away from building openings.
Central AC draws a large load when it starts. Running it on a portable generator usually needs a properly sized generator and a transfer switch or interlock installed by a licensed electrician. Plugging a generator into a wall outlet can send power back into utility lines and endanger line crews.
Put carbon monoxide alarms with battery backup on every level of the house. FEMA recommends them for any home using alternate power or heat during an outage.
Why does humidity after a long outage matter in South Florida?
A closed house without AC in South Florida heat collects moisture fast. Walls, furniture, carpets, and the inside of the air handler stay damp. EPA advises drying water-damaged areas and items within 24 to 48 hours to prevent mold growth.
After a long outage, a musty smell when the AC first starts is common. It often comes from a wet coil, drain pan, or duct insulation, not from the house. If the smell lasts more than a day or two after the system is running normally, have the coil, drain pan, and ducts checked.
What makes Hollywood, FL homes different?
Hollywood sits on the Atlantic coast in Broward County, and storm damage here often comes from wind-driven rain and flooding as much as from wind.
Hurricane season. The Atlantic hurricane season runs from June 1 to November 30, so outages and AC restarts are a recurring part of life here.
Condos. In many condo buildings, outdoor units may sit on roofs or balconies, away from the unit itself. Check with the association before anyone works on shared equipment.
Local South Florida hurricane guides, such as the City of Miami's, repeat FEMA's advice to disconnect appliances to avoid surge damage. Check Broward County's emergency management pages for local storm instructions.
Frequently Asked Questions
How long should I wait to turn on my AC after the power comes back?
Wait until the power has been steady, not flickering on and off. FEMA notes that power can return with brief surges that can damage motors. Then do a quick visual check of the outdoor unit and air handler before restarting.
Why is my AC not working after a power outage?
Common causes include a tripped breaker, a thermostat that lost its settings, a switched-off outdoor disconnect, or a built-in start delay. Storm damage, a power surge, or water in the electrical parts can also stop it. If the breaker trips again after one reset, leave it off and call a licensed technician.
Can I use my AC if the outdoor unit was in floodwater?
No. ESFI warns that powering water-damaged electrical equipment without an evaluation can cause fire, shock, or electrocution. Have the unit and its wiring checked by licensed professionals first.
Should I turn off my AC before a hurricane?
Yes. Turning the system off at the thermostat and the breaker before the power fails keeps it from restarting into a surge. It also gives you time to check it after the storm.
Why does my AC smell musty after a power outage?
When the system is off in humid weather, moisture builds up on the coil, in the drain pan, and in duct insulation. The smell often fades once the system runs and dries out. If it lasts more than a day or two, have those parts checked for mold.
Can a portable generator run my central air conditioner?
Sometimes, if the generator is large enough and connected through a transfer switch installed by a licensed electrician. Never run a generator indoors or in a garage, and keep it at least 20 feet from doors, windows, and vents.
Final Thoughts
After a storm, a few minutes of checking before you flip the AC back on can prevent a much bigger repair. If anything was underwater, damaged, or trips the breaker, leave it off and have a licensed contractor look at it.
Sources and Authoritative References
- FEMA / Ready.gov, Power Outages.
- FEMA, Be Prepared for a Power Outage (FEMA P-2143, August 2023).
- Electrical Safety Foundation International (ESFI), Water-Damaged Electrical Equipment.
- U.S. Environmental Protection Agency, Should You Have the Air Ducts in Your Home Cleaned?.
- U.S. Environmental Protection Agency, A Brief Guide to Mold, Moisture and Your Home.
- City of Miami, Hurricane Guide: Power Outages.
- NOAA National Hurricane Center, Atlantic hurricane season climatology.