Getting the AC System Ready for Hurricane Season

Why the air system deserves a place on your storm list

Storm preparation lists usually cover shutters, water, food, medicine, documents and fuel. The air conditioning system rarely gets more than a line, and yet it is one of the most expensive systems in the house and one of the most affected by a hurricane. Wind-driven rain can enter through the roof and attic and wet the ducts and insulation. Flooding can reach outdoor units and ground-level air handlers. Power outages leave a humid house closed up for days, and when power returns, a system that restarts into a damp building has a hard job.

Preparation does not mean doing a lot. It means a short list of checks done at a calm time, well before a storm is named, and a record of what the system looks like so that you can compare afterward. Much of the value comes from the record: if you have dated photographs of the air handler, the attic ducts, the outdoor unit and the drain line before a storm, you can show what changed, which helps both with repairs and with insurance conversations.

This page is about preparation, not about forecasting or evacuation. Follow the instructions of local emergency management for everything involving safety, evacuation and utilities. Nothing here replaces those instructions. Where a step involves electricity, gas or work at height, the right person to do it is a qualified professional, and this guide says so.

Our companion page, the after the storm duct checklist, covers what to do once the weather passes. Together the two pages make a before and after routine you can keep in your hurricane folder.

Start early: a calm-weather inspection of the system

The best time to look at the system is early in the season or before it, when the weather is ordinary and technicians are not overwhelmed. A pre-season look at the air handler, the filter, the drain line, the accessible ducts and the outdoor unit tells you what shape the system is in. If there is a slow drain, a damaged connection, a missing filter or a spot of moisture, it can be fixed before a storm tests it.

An evidence-first inspection at this stage produces photographs and a short written note. It records the current condition of the blower compartment and coil, the drain pan and line, the supply and return ducts that can be seen and any signs of leaks or damaged insulation. That record becomes the baseline you compare against after a storm. Our page on photo documentation explains how photographs are labeled and kept.

If the attic is accessible, have the attic ducts looked at too. Flex duct that is sagging, crushed or disconnected will perform poorly in any weather, and roof-related water entry is more damaging where ducts are already compromised. Our page on attic inspection safety explains why this is work for a trained person, because attics are hot, hard to move in and can hide unsafe footing.

Do not wait until a storm is on the way to book this. When a storm is forecast, many people want help at once, and schedules fill. A calm-season visit is simply more useful.

Filters, drain lines and the parts you can check yourself

Some preparation is simple and safe for a homeowner. Start with the filter. Find every filter location, confirm the size printed on the frame matches the slot, check the airflow arrow points toward the blower and replace a dirty filter with a clean one. A clean filter going into a storm means one less variable when the system is stressed. Keep a spare or two in the house, since stores may be short of stock before and after a storm. Our page on filter size and placement explains the common mistakes.

Next, look at the condensate drain. In many homes the drain line ends outdoors near the air handler's drain outlet, or at a visible pipe. Check that water drips from it when the system runs in humid weather, and that the area around it is clear of leaves, mud and debris. A drain that is slow or blocked in ordinary weather will be worse when humidity is extreme. Do not push wires or tools into pipes you do not understand. If the drain looks wrong, have a qualified technician clear it. Our page on condensate drain pan and line describes the parts.

Check the area around the air handler. Items stored in the closet or garage next to the equipment, such as cardboard boxes, paint cans and cleaning supplies, can block airflow and, if they get wet, add to the mess. Clear a working space in front of the unit so a technician can reach it quickly afterward.

If you have a float switch or an overflow pan, note where they are. Do not alter them. Their job is to stop the system or catch water when the drain backs up, and a technician can confirm they are working.

The outdoor unit and what surrounds it

The outdoor condensing unit sits in the weather and is often the first part to be damaged. Look at what is around it. Loose items such as patio furniture, toys, planters, tools and bins can become projectiles in high wind, and they can strike the unit. Secure or bring in what you can, in line with local advice, and trim nothing yourself that requires climbing or power tools in unsafe conditions.

Check that the unit stands level on its pad and that the pad is not undermined by erosion. Look for vegetation growing close to the coils, which restricts airflow and collects debris. Keep a clear space around the unit as part of normal maintenance, not as a last-minute chore. If there are strap-down brackets or other anchoring in your area, ask a qualified HVAC contractor whether they are appropriate for your unit and local requirements. That is not a do-it-yourself job.

Do not cover the unit with a tarp or plastic and leave it covered while it runs. A covered unit can overheat and be damaged. After the system is turned off for a storm, some homeowners ask about covering. The correct answer depends on the unit and local guidance, so ask your HVAC contractor rather than improvising.

Take photographs of the outdoor unit from several angles before a storm, including its data plate if it is readable. If the unit is damaged or lost, those photographs and the model information help with replacement and with insurance.

Shutting the system down safely before a storm

Whether and when to shut the system down depends on the situation. If an evacuation is ordered, or if flooding or a storm surge is expected at your property, turn the system off at the thermostat as part of leaving, and follow instructions from emergency management about utilities. If you are staying in place and the power is on, many people run the system as long as it is safe to do so and then shut it down when the power goes out or when conditions turn dangerous.

The thermostat is the safe place to stop the system. Setting it to off stops the call for cooling. Do not open the electrical panel, handle wiring or operate disconnects near the outdoor unit in wet or windy conditions. If your household has been advised to turn off power at the main for flooding reasons, follow that guidance from the utility or emergency officials, and understand that those steps are for qualified people when there is any risk of water contact.

Before leaving, some people lower the thermostat temperature to pre-cool the house, which gives some extra time before the indoor temperature climbs after an outage. Do this only when it is safe, and not at the cost of leaving or sheltering on time. Closing interior doors can also slow the spread of heat and humidity, but fresh air and ventilation concerns apply if the house is closed up for a long time.

Write down the steps you took and the time, and take a last set of photographs of the thermostat setting and the air handler closet. Our page on power outage and AC restart covers what to do when the power returns.

What to photograph before the storm

Photographs should be dated. Most phones add a date automatically in the file details. Store them in a folder named for the property and the year, and copy that folder to a cloud account or a second device. Printouts and paper records are also useful if power or the network is down.

The goal is to establish what things looked like before. After a storm, a ceiling stain, a wet air handler closet or a dust trail from a register is much easier to interpret when you can see whether it was there before. Our page on keeping your own duct records suggests a simple layout.

Do not climb onto the roof, work at height or enter a hot attic alone to take photographs. If those spots matter, have a professional photograph them during a calm-season inspection.

• The air handler closet or location, wide and close, with the filter slot visible.
• The data plates on the air handler and the outdoor unit, if readable.
• The drain line outlet and the area around it.
• Accessible ductwork in the attic or ceiling, including connections and insulation, if it is safe to reach.
• The outdoor unit from at least three sides, plus its pad and surroundings.
• The thermostat and its settings.
• Ceilings, walls and floors near registers and the air handler, so existing stains are on record.
• The roof and any visible damage or weak points, from the ground only.

Humidity, closed-up homes and what the system faces after an outage

After a hurricane, the usual problem is not wind but time without power. A sealed, warm house in South Florida's humid climate rises in indoor humidity quickly once cooling stops. Surfaces that were dry become damp, and materials such as fabric, drywall and wood start to absorb moisture. If the outage lasts days, the conditions can support growth on surfaces in the house, and a system that restarts into that environment carries the humid air through the ducts.

This is why a pre-storm check matters. A system with a clean filter, a clear drain and tight, well-insulated ducts copes better with a restart than one with a clogged drain or sweating, damaged insulation. It is also why the post-storm steps focus on drying, ventilating when conditions allow and checking before assuming everything is fine.

Where a house was closed up for a long time, a musty smell on restart is common. The smell does not on its own identify what is happening, and it should be checked rather than masked. Our page on post-hurricane duct concerns explains what causes it and what an inspection looks at.

If your property is vacant during the season, such as a seasonal home, these concerns are larger, because no one will be there to notice a problem. Our page on snowbird seasonal home duct guidance covers arrangements for unoccupied homes.

Condos, rentals and shared systems

If you live in a condominium or rent, your role is different. The building may control the central systems, the roof and the common areas, and your responsibility may stop at the unit's air handler and filter. Read your association rules or lease to understand who handles what, and ask the manager what the building's storm procedure is for air systems, elevators and power.

Document your unit before a storm in the same way: the air handler, the filter, the drain, the ceilings and the thermostat. Notify the manager of any existing problems so there is a record. After a storm, report damage promptly in writing and keep copies.

In a high-rise, individual units often have a compact air handler or fan coil and a condensate line that ties into a shared system. A backed-up common drain can cause water in several units at once. Our page on deciding for a condo unit versus a building explains how responsibility is divided, and how to approach a building-wide issue.

If you rent, tell your landlord about anything you notice during preparation, such as a stained ceiling near the air handler. Ask who to call after a storm and how they want problems reported. A clear plan before the weather arrives saves time afterward.

A simple preparation routine and when to call

A workable routine looks like this. Early in the season, book a calm-weather inspection with photographs. Change the filter and keep spares. Check the drain outlet and the outdoor unit surroundings. Photograph the system. Write down who to call, and keep that information in your storm folder. As a storm approaches, secure loose items, take final photographs and follow the guidance of local officials about utilities and evacuation.

Do not use the approach of a storm to start a project that requires opening the air handler or working with electrical components. Those steps belong to qualified people at calm times. Leave panels closed, do not spray anything into the ducts and do not tape over registers or returns as a storm measure, since that can cause its own problems when the system restarts.

If you have a specific concern, such as a history of water in the attic, a slow drain, a smell or an old system, call and describe it. Quotes are given by phone only, and a complicated situation may need an on-site visit with a service call charge explained before dispatch. Call whenever you are ready, and preferably before a storm is named, so the time you have is used well.

Questions people ask

Related pages

• After the Storm: A safe order of checks for your AC and ducts once a storm passes: what to verify before restarting, what to photograph, and when to call a professional.
• Power Outage: What to check before restarting cooling after a South Florida power outage, why a short wait helps, and when ducts and drains deserve a closer look.
• After a Hurricane: After a hurricane, ducts may have taken on water, debris or humidity. Learn what is safe to check yourself, what to leave to professionals and what comes first.
• Photo Documentation: Before and after photos are only useful if they are honest. See what a good duct photo set contains, how it is labeled and how to spot a misleading one.
• Dryer Vent Reroute: When a long or bent dryer vent run justifies a new path, what evidence points to rerouting, and why the work should be done by someone qualified.
• Seal First: The order of duct repair, sealing and cleaning, and why it matters: leaks that feed dust, work that stirs it up and how to sequence jobs in a Florida home.