Leading Cooling and Heating

Hurricane season: protect your AC before and after the storm

What to do with your heating and cooling system when a storm is coming, when the power goes out, and before you turn it back on.

On this page
  1. Your storm checklist
  2. Generators and carbon monoxide
  3. If your equipment flooded
  4. Restarting after a long outage
  5. Common questions
  6. Sources

Key takeaways

  • Never run a portable generator inside your home, garage or carport. The CDC says to keep it at least 20 feet from doors, windows and vents.
  • If floodwater reached your indoor or outdoor unit, don’t turn it on. Have it checked and cleaned first.
  • During an outage, set the thermostat to OFF. Turn the system back on once power is steady.
  • Clear debris from the outdoor unit, with the power off, before running it after high winds.

Your storm checklist

Most storm damage to HVAC equipment comes from flooding, flying debris and power surges. A few minutes of preparation helps, and so does knowing what to check before you restart.

Interactive tool

Hurricane season checklist

Work through it before and after a storm. Your progress is saved in this browser, and you can print it for your emergency kit.

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Generators and carbon monoxide

Generator and flood safety at a glance
CO20 ft +12345

  1. 20 feet or more

    Generators stay outdoors, well away from doors, windows and vents.

  2. Exhaust away from homes

    Point the exhaust away from your home and your neighbors’.

  3. CO alarm inside

    Battery-powered or with battery backup, on every level and outside sleeping areas.

  4. Flood line

    If water reached the unit’s electrical parts, don’t run it.

  5. Outdoor unit

    Clear debris and check for damage before restarting.

Never plug a generator into a wall outlet to power the house. That’s called backfeeding, and it can injure utility workers and neighbors. A licensed electrician can install a transfer switch the right way.

If your equipment flooded

Outdoor units are built for rain, not for sitting underwater. FEMA notes that the control and power parts in HVAC equipment aren’t designed to withstand floodwater. The CDC advises having a flooded system checked and cleaned before you turn it on, because a contaminated system can spread mold through the house.

  • Leave the system off, even if it looks dry.
  • Photograph the water line on the equipment for insurance.
  • Have the indoor unit, ductwork and electrical parts inspected.
  • Ask whether ducts that sat in floodwater need cleaning or replacement.

Restarting after a long outage

  1. Wait for steady power

    Flickering power and surges are hard on motors and electronics.

  2. Check the outdoor unit

    With the power off at the shutoff box, clear debris and look for bent fins, damage or a unit knocked off its pad.

  3. Turn the breaker and thermostat back on

    Set cooling a few degrees below the room temperature.

  4. Watch and listen

    Make sure both units run and the air turns cool within about 15 minutes. Turn it off if you hear grinding or buzzing, or see sparks.

Common questions

Clearing loose objects that could be thrown into the unit matters more. If you do cover it, remove the cover before turning the system back on.
Only if the generator is large enough and connected through a properly installed transfer switch. Starting an AC compressor takes a burst of power, so ask an electrician about sizing.
No. Outdoor units are designed for rain. Flooding, where water rises over the base and into the electrical parts, is the problem.

Sources

We checked the facts in this guide against these public sources.

This guide is general information for homeowners, not a diagnosis of your system. If you smell gas or a carbon monoxide alarm sounds, leave the house and call 911 or your gas utility first.

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