Air conditioning repair across Suffolk County, Long Island.

The thermostat says 72 and the hallway says 80. The outdoor unit is running but the air from the registers is not cold. The system runs all afternoon and never shuts off. The upstairs bedrooms are ten degrees warmer than the living room by three in the afternoon. There is water staining the ceiling under the attic air handler. Something outside is buzzing and the fan on top of the condenser is not turning.

Those are the calls. They come from a run capacitor that has drifted out of tolerance, a pitted contactor, a seized condenser fan motor, a compressor drawing locked-rotor amps, a dirty evaporator coil, a clogged condensate drain with a failed float switch, a blower wheel loaded with dust, a restricted thermal expansion valve (TXV — the device that meters refrigerant into the indoor coil), or a real leak at a flare, a service valve, or a corroded coil. Several different faults produce the same symptom, which is why the next section exists.

The call starts with confirming the complaint with the homeowner — what the house is doing, what the thermostat is set to, how long it has been going on. Before anything else, we check the thermostat and the filter. A system starved of air reads like a charge problem and a filter nobody changed is the most common cause of a frozen evaporator coil.

We pull the disconnect at the outdoor unit and check the electrical side: the contactor (the heavy-duty switch that sends power to the compressor and fan), the run capacitor against its rated microfarads, the condenser fan motor and its amp draw, and the wiring at the box. Inside, we check the blower, the evaporator coil, the condensate drain, and the float switch that is supposed to shut the system down before water finds the drywall.

Then we take pressures and temperatures — the temperature split across the coil, the suction and liquid pressures against the outdoor temperature, superheat and subcooling, the amp draw on the compressor and fan motor, and the static pressure across the duct system. We explain the finding in plain English and what the repair involves, then do the repair if the homeowner wants it done. Travis Hart is the person on the job, not a dispatcher who hands it off.

If the call turns out to be on a ductless system rather than central air, the work is different — ductless mini-split installation and service covers that equipment separately.

A technician is reading the supply and return air temperature split across the indoor coil — the difference between what goes in and what comes out. We read suction and liquid pressures against the outdoor temperature, and we calculate superheat (how much extra heat the vapor carries past the evaporator) and subcooling (how much the liquid has been cooled below its condensing point), because each one tells us whether the charge is right and where the metering device is. We check the amp draw on the compressor and the fan motor, the capacitor microfarads against the rating printed on the can, and the static pressure across the duct system to see whether the system can breathe.

"Just add some refrigerant" is not a repair. A sealed system that is low is a system with a leak, and putting refrigerant in without finding the leak means paying for the same call again next summer. A frozen evaporator coil has to be thawed before anything can be read accurately, which is exactly why airflow and the filter get checked first — a frozen coil gives you pressures that mean nothing until it is clear and running again.

Most of the housing stock in Suffolk County is post-war. A large share of these houses were built with hot water baseboard or steam heat and had central air added decades later, so the air handler ended up in an attic or a crawlspace instead of in a proper mechanical room, and the duct was run wherever it could physically fit.

Flex duct in an unconditioned attic that has been crushed, kinked, disconnected at a boot, or is running through 130-degree air in July is a common find here. Undersized or missing returns starve the system and the coil freezes. An attic air handler over finished ceilings is a liability when the condensate drain clogs and the secondary pan or float switch is missing or failed — the first sign is a stain on a bedroom ceiling.

On the South Shore, salt air is the real variable. Condensers within reach of the water corrode — the fin stock goes chalky and thin, the copper hairpins and the coil-to-line-set joints pit, and the disconnect boxes and contactors corrode. A coil that looks intact from the outside can be shedding fin material and rejecting heat badly. What this means for the diagnosis: the pressures read high, the homeowner assumes refrigerant, and the actual problem is that the coil cannot get rid of heat.

Cottonwood and pollen in early summer mat the outdoor coil solid. Outdoor units set on the ground in low, wet yards, and units that sit under a deck or against a fence with no clearance to breathe, are common here and they underperform for reasons that have nothing to do with refrigerant.

A working R-410A system is not obsolete and does not need to be replaced because of the refrigerant rules — R-410A remains available for servicing existing systems. The full explanation of the R-410A refrigerant change is on its own page; this one stays with the repair.

The real repair-or-replace factors are questions, not a verdict: how old is the system, has the compressor itself failed, is the leak in a coil or in a line set buried in a wall, has the same system been repaired repeatedly, and is the ductwork the actual problem — in which case a new condenser fixes nothing. We will tell a homeowner when a repair is the better call even though the replacement is the bigger job. If the path is replacement, that conversation starts on the AC installation and replacement page. Regular seasonal tune-ups and inspections catch a dirty coil or a drifting capacitor before it becomes a no-cool call, and if the problem is heat rather than cooling, heating repair is where that starts.