The water is gone. Now decide what the air conditioner is worth.

The first hour

1. Do not run it. If the system is running, turn it off at the thermostat and then at the outdoor disconnect. A compressor that starts with salt water in the control compartment can short the contactor or arc the terminals, and a blower motor that starts wet can finish itself off.
2. Photograph the water line. On the outdoor cabinet, on the air handler if it got wet, on the wall beside it. Do it before the line dries and before anyone wipes it. This is the single most useful thing you can do for both the repair decision and the insurance claim.
3. Note the water. Was it the tide coming up the storm drains, which is salt? Rain pooling in a low yard, which is fresh? Surge over the seawall, which is salt and carries silt? The answer changes everything below.
4. Leave the panels on. Opening the unit and poking at wet electrical parts helps nobody. Call and describe what you see.

The salt-versus-fresh rule

Fresh water is an inconvenience. Salt water is a chemical event. Fresh rainwater that pooled around a condenser and never reached the electrical compartment leaves silt on the base pan and needs a rinse and an inspection. The same depth of brackish tide water, or surge off the Matanzas, leaves salt on every metal surface it touched. That salt stays after the water evaporates and keeps working on terminals, windings and copper for weeks.

Most St. Augustine flooding is salt or brackish. The king tides that put water across Davis Shores, the bayfront and the low streets of Lincolnville come up through the storm drains from the Matanzas. The surge from Matthew, Irma, Ian, Nicole and Milton was ocean. If your street flooded, assume salt unless you watched it rain into a puddle.

Part by part: the outdoor unit

Component	Where it sits	Fresh water, shallow	Salt water, any depth that reached it
Base pan and cabinet	Bottom	Rinse, check for silt	Rinse, expect accelerated rust
Coil and fins	From an inch above the base	Rinse from inside out	Rinse immediately; salt in the fins corrodes the coil
Fan motor	Top	Usually fine	Usually fine unless water reached the housing
Contactor	Low in the control compartment	Dry and test; often fine	Replace
Capacitor	Low in the control compartment	Dry and test	Replace
Compressor plug and terminals	A few inches up the compressor	Inspect	Clean, treat and test; replace compressor if corroded
Compressor windings	Sealed inside	Fine unless submerged	Test insulation resistance; a submerged compressor is suspect
Control board, if present	Varies	Dry and test	Replace
Disconnect and whip	On the wall	Fine if above water	Replace if wet

The pattern is simple. The parts that fail from flooding are the low electrical parts, and salt turns “dry and test” into “replace” across the board. A unit whose water line is below the control compartment is almost always savable. A unit whose compartment took salt water needs new electrical components at minimum, and if the water reached the compressor terminals, the question becomes whether a unit of that age deserves the money.

Book a flood inspection

Part by part: the air handler

Indoor units fare worse, because their vulnerable parts sit lower and because of the insulation. A slab-mounted air handler in a closet or garage that took even a couple of inches of water has a wet blower motor, a wet control board, and wet fiberglass insulation inside the cabinet that will never dry clean. The first run of duct off the unit often has wet insulation too. Mold follows within days in this climate. We rarely recommend saving a flooded air handler; the exception is a unit whose water line stayed below the bottom of the cabinet because it was already on a platform.

An attic air handler is unaffected by street flooding, which is one argument for the attic that we otherwise seldom make.

The age test

After the component verdicts, the last question is the unit’s age. New electrical parts and a cleaning on a six-year-old condenser that took a few inches of salt water is money well spent. The same work on a fourteen-year-old unit with thinning fins buys a year or two at most, and the next flood will take the compressor. When the repair estimate passes about a third of a replacement on a system past its mid-teens, we put the two quotes side by side and let the numbers speak.

Replacement after flooding comes with a stand or wall bracket set above the water line you photographed in the first hour, a coated coil for the salt, and the disconnect mounted high. Those three details are the difference between this being the last flood inspection and the first of several.

The paper trail

Every flood inspection ends with a written report: the water source and depth as described, photographs of the water line and the component condition, a list of what is damaged and what is not, the age and model, and a quote for the repair and, where it applies, the replacement. Adjusters in this county see a lot of these after a tide season and know what to look for. Having it in hand the week of the event is far easier than reconstructing it in August.