A summer squall can roll through in ten minutes and leave a full day of headaches behind. I have seen brand‑new air conditioners torn open by golf ball hail, attic air handlers drowned by wind‑driven rain, and outdoor disconnects blown off the wall. Some systems limp along for weeks after a storm, running hot and drawing more power, until a small problem snowballs into a compressor failure. Knowing what to check right after the weather passes makes the difference between a simple visit from an hvac company and a major emergency ac repair with long lead times and serious costs.
Storms hit HVAC systems in a few predictable ways: direct impact from debris, electrical surges and brownouts, short‑term flooding, and infiltration of water into components that were never designed to be wet. The checks below reflect hard lessons from roofs, crawlspaces, and backyards where the wind had its say.
Safety first, and what not to do
The most expensive mistake I see is flipping a breaker back on while water still sits inside the equipment. Just because a blower hums or a condenser fan spins does not mean the system is safe. If you suspect water or electrical damage, do not restart your AC. The second mistake is removing panel covers without pulling disconnects. Many residential condensing units keep live line voltage present even when the thermostat is off.
If the equipment area is flooded, wait until water recedes below equipment level and any standing water around electrical boxes is gone. If you smell hot insulation or see scorched wiring, leave power off and call for emergency ac repair. An hvac company will have insulated tools, a meter rated for the job, and the judgment to decide what can be salvaged.
Start outside: the condensing unit in real weather
The outdoor unit takes the storm head‑on. After the sky clears, walk the perimeter slowly and look as if you were buying a used system and wanted every flaw to be obvious. Fan blades are thin aluminum or composite, easy to bend if a twig gets pulled in. A blade striking a bent shroud can shear a motor shaft in minutes. I run a finger along the top grille to feel for wobble in the motor mount. If the unit looks tilted, measure from pad to cabinet at two corners; even a half inch of lean can strain refrigerant lines or cause oil pooling in the compressor.
Hail tells its own story. Light hail dimples aluminum fins, which reduces airflow and raises head pressure. Baseball hail can puncture coils outright. Shine a flashlight across the coil face to catch shadows. If fins are flattened across broad areas, efficiency will suffer until a fin comb opens the passages. A coil puncture, even a pinhole, usually shows up as an oily stain and a sweet odor. That calls for professional leak detection and rarely ends with a cheap fix.
Wind can push yard mulch and leaves into the coil like a filter. I have opened cabinets packed so tight that the fan was starving for air. Do not pressure‑wash at an angle because you can fold fins over. A garden hose and a gentle vertical rinse from inside out is safer if power is off and access panels are replaced afterward.
Check the electrical service whip, the disconnect, and any exposed conduit. A pulled seal tight fitting or a cracked disconnect box lets rain drive straight onto live lugs. Rust at the fuse clips or breaker face is a warning. If lightning hit nearby, surge damage often shows up here first: pitted contacts, blackened plastic, swollen capacitors inside the condenser. A swollen capacitor has a domed top that should be flat; treat it as failed even if the fan still runs. I keep spare capacitors because a ten‑minute swap can save a service call when everything else is sound, but if your system is under warranty or you lack a meter to verify microfarads and wiring, wait for ac repair services. A miswired capacitor can fry a motor in seconds.
Finally, look at the refrigerant lines where they exit the wall. The larger suction line should have intact insulation. Storms often strip it away, and exposed copper sweats. That condensate can run back along the line into wall cavities, and you lose efficiency. Reinsulating is cheap and effective. More critical is any sign of rub marks or kinks from movement. A kinked liquid line will starve the metering device and overheat the compressor.
Flooding: what is submerged can be saved, and what cannot
Condensing units that went under water can sometimes be salvaged if the water line stayed below the electrical section and the motor windings never soaked. In practice, once water reaches the control compartment, the list of parts to replace grows long: contactor, capacitor, fan motor if water reached bearings, and often the compressor terminal plate. Silt is the enemy. Even after drying, fine grit acts like valve‑lapping compound in bearings and seals.
Indoors, a crawlspace air handler that sat in floodwater needs more than a rinse. Sheet metal soaks at seams, insulation becomes a mold sponge, and blower housings trap silt. I have seen homeowners spend a weekend scrubbing only to call back two weeks later with odors and a tripped breaker. If floodwater reached the blower deck or the control board, plan for replacement of the affected assemblies and thorough sanitation of the duct connection points. Insurance adjusters usually side with replacement once contaminated insulation is involved.
Power quality after the storm: surges, sags, and silent damage
Utilities do not snap back to perfect voltage after grid damage. Brownouts are common. A compressor that tries to start on low voltage draws high current and overheats quickly. The symptom can be subtle: the outdoor fan runs, the compressor hums and trips on thermal protection, then resets and tries again. If you hear that cycling, cut power and call for hvac services. A hard start kit might get a tired compressor off the ground in normal conditions, but it will not fix a grid sag and can mask a failing winding.
Lightning rarely strikes equipment directly, yet nearby strikes induce voltage spikes that taste expensive. Circuit boards die quietly. Thermostats boot with blank screens. Some systems log fault codes that help a technician pinpoint a damaged transformer or shorted low voltage circuit. If you have a surge protector on the condenser or at the panel, note its indicator light. A tripped protector often sacrifices itself and deserves replacement even if the system seems fine.
Water where it should not be: ducts, returns, and drain systems
Wind‑driven rain finds leaky duct seams and attic returns. I have pulled filters that looked like wet cardboard, then traced water marks up a wall to a return grille with a gasket missing for years. After a storm, remove the filter and feel for dampness around the frame. If the filter is soaked, leave the system off until the source is found. Running a system with a wet return invites mold growth on the coil and in the plenum.
Condensate drain lines deserve attention after outages. Power failures leave air handlers idle while humidity stays high, and storm debris sometimes clogs exterior drain terminations. When the system restarts, water can back up, trip float switches, or overflow. Inspect the drain pan under the indoor coil with a flashlight. If you see standing water or rust streaks, clear the drain before full operation. A simple wet‑dry vacuum at the exterior drain line often pulls out algae and silt. If your air handler has a secondary pan, look for water marks and check the pan switch if installed. I have caught many leaks at this early sign, saving ceilings from collapse.
Refrigerant linesets and joints after impact
Flying branches are not picky. A dented lineset may look harmless but can cause restrictions. The system will still cool on a mild day, then fail on the first 95 degree afternoon. You can infer a restriction without gauges by feeling the suction line near the air handler after ten minutes of operation. It should be cold and sweating lightly. If it is barely cool while the condenser runs hard, or if the liquid line feels hotter than usual, call for an inspection. A professional will check superheat and subcooling to confirm. For homeowners, the cue is performance dropping after the storm with no obvious reason.
Brazed joints at the outdoor unit sometimes crack when the cabinet shifts. Oily dirt around a joint is a tell. Do not wipe it away before a technician arrives, because that stain helps locate the leak. Refrigerant loss is not just a cooling issue; low charge can overheat the compressor and shorten its life. The right repair is to fix the leak, evacuate properly, and weigh in charge. Topping off without finding the leak is a short road to another call.
The roof and attic factor: packaged units and splits up high
Roofs take the worst wind. Packaged units on curbs can lift and settle crooked, breaking the weather seal. I check for shiny new gaps in old mastic, displaced hail guards, and loose service panels. A panel that left its screws somewhere in the storm has also let gallons of water into the electrical bay. Bring a flashlight and a healthy respect for edges if you climb to look.
In attics, flex duct connections get yanked when the roof deck flexes. Tug gently at the outer jacket and confirm the inner core is still taped and clamped to the collar. Even a two‑inch gap can pull hot, dusty attic air into the return, which both overwhelms the coil with heat load and coats it with insulation fibers. If you find a gap, resist the quick fix of duct tape. Use mastic or UL‑181 tape and a new clamp, or have an hvac company button it up. While you are up there, check that the secondary drain line from the coil pan, if present, exits over a window or other visible spot. If water drips there, the primary drain is clogged.
The thermostat and controls: small brains, big influence
Electronic thermostats can glitch after power https://rowanhrvo881.tearosediner.net/how-to-read-an-hvac-company-maintenance-agreement events. If the screen is blank, verify that the indoor unit’s breaker is on and the service switch near the air handler is engaged. Some systems have a low voltage fuse on the board, usually 3 to 5 amps. A shorted outdoor contactor coil after a surge will blow that fuse instantly. I carry a pocketful of them on storm weeks. If you replace a fuse and it pops immediately, do not keep feeding it. A short needs to be traced, often starting at the contactor or the wiring where it rubs a sharp cabinet edge.
Smart thermostats sometimes revert to defaults after long outages. Check that cooling mode is selected and temperature setpoints make sense. I have seen homes stuck at 78 while the owners swore the air “wasn’t working,” only to find the schedule set that way after a firmware update.
When to try a restart, and how to do it without harm
There is a safe way to test your system after basic checks. Confirm no standing water, no obvious electrical damage, and clear drains. Replace a soaked filter with a dry one. Restore power at the breakers first, then the outdoor disconnect, then set the thermostat to cool.
Give the system ten minutes to stabilize. Walk outside and listen. A healthy condenser makes a steady motor sound with a faint hiss of refrigerant flow. Loud buzzing without compressor engagement means trouble, likely a capacitor or contactor damaged by surge. Inside, feel the supply air; it should cool rapidly within five minutes. If the evaporator coil ices due to restricted airflow or low charge, you will see frost at the indoor unit within twenty to thirty minutes. If anything looks or sounds off, shut it down and move to ac repair services. It is far cheaper to leave a house warm for a few hours than to run a compressor into failure.
What emergency ac repair typically covers after a storm
A good hvac company will triage storm calls. During the first 24 to 48 hours, they focus on restoring safe operation, not full tune‑ups. Expect them to inspect electrical components, test capacitors and windings, verify refrigerant pressures if the system appears tight, and clear drains. If water intrusion is confirmed in the air handler, they may recommend temporary dehumidification and ventilation until parts arrive. For rooftop equipment, they will often coordinate with roofers to reseal curbs and penetrations before powering up again. The right move is to ask for a written scope: what is safe to run now, what needs replacement, and what the risks are if you defer anything.
I have had customers ask whether to replace a hail‑dented condenser that still works. The answer depends on coil fin damage density. Light cosmetic dents are mostly an efficiency hit. If more than a third of the face area is flattened or punctured, replacement makes sense. Insurance policies often cover hail on HVAC equipment. Document with photos and model numbers before any work.
Preventive steps to take before the next storm
Storms are not a matter of if. They are a matter of when. Simple steps add resilience. A properly anchored condenser pad resists movement. A hail guard kit costs less than a service call and protects coil faces without strangling airflow if sized right. A whole‑home surge protector at the main panel plus a dedicated protector at the condenser keeps most spikes from cooking controls. Elevating air handlers in flood‑prone crawlspaces by even six inches can put them above typical waterlines. Keeping the yard clear of lightweight gravel and bark near the unit reduces the sandblaster effect when wind kicks up.
If you have a standby generator, coordinate load shedding so the air conditioner does not slam the generator on first start. Soft start kits, when specified correctly, reduce inrush and make generator operation more forgiving. Not every compressor tolerates them equally, so involve an experienced technician rather than ordering one blindly.
What homeowners can reasonably handle, and where to draw the line
Plenty of post‑storm checks fall into homeowner territory: visual inspections, filter changes, clearing debris from around the unit, rinsing coils gently, checking drains with a shop vac, and verifying thermostat settings. Replacing line set insulation is fair game. Beyond that, the calculus changes. Opening a condenser’s control section exposes live parts, and even when power is off, stored energy in capacitors can bite. Brazing a cracked joint or weighing in refrigerant requires tools and training. Trial‑and‑error part swapping often ends with new parts aligned with old problems.
Emergency ac repair is not only about fixing what the storm broke. It is also about confirming that hidden damage will not surface on the first hot spell and strain your system to death. The value in calling seasoned ac service techs lies in that second part. A careful tech reads the clues: a slightly noisy contactor, a fan blade with hairline cracks from hail, a blower motor whose bearings sound dry after a day in humid air. Replacing a $30 part today can save a $900 call next month.
A practical, minimal kit for storm season
For households in storm belts, it pays to keep a small kit near the mechanical closet: spare filters in the right size, a flashlight, a wet‑dry vacuum nozzle dedicated to the condensate drain, UL‑181 tape for duct emergencies, and a rain cap for the exterior drain termination if wind drives water into it. Note the brand, model, and serial numbers of your equipment, along with the values on your capacitors and contactor coil voltage, in a notebook or phone photo. When you call for hvac services on a high‑volume day, having that information handy can speed parts matching.
Cost expectations and timing during peak demand
After a major storm, hvac company schedules fill fast. Many run triage: no‑cool or unsafe conditions first, then partial cooling issues. Expect arrival windows rather than exact times. Pricing varies by region, but some patterns hold. Electrical component replacements tend to be same‑day and modest compared to refrigerant circuits or blower assemblies. Water‑intrusion repairs escalate when ductwork or insulation is contaminated. If insurance is involved, ask your contractor to document with photos and to separate immediate safety repairs from restoration items. Adjusters often approve the former quickly and deliberate over the latter.
One more practical note: parts availability swings wildly after regional storms. If your condenser is older than about 12 to 15 years, critical components may be special order. In those cases, it can be faster to replace the condenser than to wait a week for an OEM motor. An honest assessment from a trusted ac repair services provider helps here. I have guided homeowners both ways based on expected lead times, system age, and the rest of the equipment stack.
A real‑world example
Two summers ago, a line of thunderstorms tore across a neighborhood of single‑story homes. I reached a house where the outdoor unit looked almost untouched. The fan spun, the compressor tried, then tripped. Inside, the air handler was quiet and dry. At first blush, I expected a weak start capacitor from a surge. The capacitor tested within spec. The contactor showed slight pitting, nothing dramatic. Then I noticed the condenser cabinet sat a quarter inch askew on the pad and the liquid line had a faint crease where it left the service valve. Oil film at the flare nut sealed the case. The branch that hit the unit had shifted it enough to stress the joint, create a micro‑leak, and drop charge just enough that the compressor could not start under head pressure. We repaired the leak, performed a proper evacuation, replaced the filter drier, weighed in charge, swapped the contactor as a preventive, and secured the cabinet to the pad. The system ran like new. The only visible clue to a layperson was that tiny oil halo. This is the kind of hidden damage storms leave behind.
What to check, briefly, when time is tight
- Outside: cabinet level and intact, fins not crushed, fan blades true, disconnect and wiring undamaged, no oil stains on coil or fittings, debris cleared 2 feet around. Inside: filter dry and seated, drain pan empty and drain line clear, no water marks around return, thermostat powered with correct mode and setpoint.
If any of these checks raise questions, skip the restart and call for emergency ac repair. Two minutes of caution beats two weeks of waiting for a compressor.
The bottom line after the clouds lift
Storms do not have to end in catastrophic HVAC failures. Most post‑storm problems start small and announce themselves if you know what to look for. Treat water and electricity with respect, verify airflow paths and drainage, and listen to the system’s startup behavior. When in doubt, lean on professional ac service. A qualified hvac company will stabilize your cooling quickly, spot the less obvious weaknesses, and give you a plan that balances budget, safety, and comfort.
The best systems survive storm season not by luck, but by preparation: sound installation, thoughtful protection, smart electrical safeguards, and a homeowner who knows when to look, when to wait, and when to pick up the phone.
Prime HVAC Cleaners
Address: 3340 W Coleman Rd, Kansas City, MO 64111
Phone: (816) 323-0204
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