Why Has My Hitachi Aircon Started Leaking Water Indoors?

A leak sorts faster by date than by where the puddle sits. Ask when the first drip appeared, and what changed in the days before it. That one answer usually names the fault.

The mechanism is plain enough. A cold coil, damp air, condensation, a tray to catch it and a fall to carry it outside. A leak says the water halted on that path.

Cooling is usually unaffected, which throws people off. The cold side has not failed. A room that still chills while water drips is pointing at the drain, not at the machine.

A drain fault rarely arrives at random. It arrives after something. Wet weather, a service visit, a power cut, or years of quiet buildup reaching a threshold. Each leaves a different signature in the calendar.

Note the days it drips and the days it stays dry. That short record does more work than a photo of the stain.

A drip that comes and goes is a volume problem. The drain works, just not fast enough for the water arriving. A drip at the same rate every day is physical. Something is broken or fully closed off.

A drip that starts right after an event usually belongs to that event. Three days after a service visit, or one day after a power cut, is not coincidence.

A pipe that leaks only in humid weather is almost never cracked. A crack passes water at the same rate whatever the weather. Humidity changes how much condensate the coil makes, so that drip is about volume.

The mechanism is scale. Minerals in the condensate settle on the inside wall of the pipe, layer on layer, and gather fastest at joints. Over ten or more years they narrow the bore at one point without closing it.

That narrow point passes ordinary output without trouble. On a humid afternoon output climbs. Water then reaches the restriction faster than it can pass, and backs up to the tray and over the lip.

Finding it means tracing the run from the unit to the discharge point, checking each joint, then opening the affected section and clearing it. A flush from the tray end alone can miss a restriction well downstream.

The standard quote in an older home is hacking the wall to replace buried pipe. Scale does not require that.

Cassette and ceiling concealed units lift condensate with a pump. Wall units usually drain on fall alone. That single difference adds a fault a wall unit cannot have.

The pump on such a unit can hold an internal safety cut off that stops the motor when it senses an abnormal condition. Clearing that state takes one clean break in supply. Power simply returning does not always count.

Building power cuts often flicker before they settle. The unit comes back and cools normally while the pump stays in its protective state. Condensate collects with nothing lifting it out, and water shows at the ceiling panel within a day.

The tell is that the unit behaves perfectly between outages, sometimes for weeks. Wear does not switch itself on and off like that. A pump silting up gets worse steadily. A stuck one is either fine or dead.

Three checks cost almost nothing and belong before any quote is written.

Check the drain outlet for a cap or cover. Servicing seals the outlet temporarily, and the cap is invisible once the panels close. If the backup started within a week of a visit, rule this out first.

Power cycle the pump on a ceiling unit. Off fully, pause, back on. If the drip followed a power cut, that can end it.

Trace the drain run and check the joints. That takes longer, but it is cheaper than opening a wall, and it is where an intermittent drip usually resolves.

Turn the unit off in the meantime where water is landing on wiring, a socket, or anything inside a ceiling or wall build-up. Otherwise it can wait. A running coil only makes more water to spill.

Be wary of a quote that opens with hacking, a pump swap, or a chemical overhaul. Any of them may turn out to be the answer. None of them is a diagnosis.

Ask what was checked and what was found before those were recommended. A drain fault leaves evidence: sludge in the tray, scale at a joint, a capped outlet, a pump that will not run. If none of that turned up, the quote is a guess.