Why is my Mitsubishi Electric aircon leaking water indoors?

The water is condensate. Room moisture forms on the cold coil, drips into a tray below, and leaves through a pipe.

In the pattern that dominates this fault, the water reaches the tray. It gets out further along, at a connection. A hose clip, a pan a few millimetres off its rails, a nut left hand-tight, a pump cover not seated square.

A joint leak and a choked pipe look identical from the floor. Only one is cured by flushing the line.

It also explains the version that wears people down. A flush stops the drip, then it returns on the next long run. Flushing proves water can move, not that the route stays watertight.

A unit dry yesterday and dripping today points at whatever was touched yesterday. One that stays dry all morning and wets the floor by evening fails only under load.

Volume is the reason. A coil running four hours makes more water than one running twenty minutes. A slightly loose joint passes the small volume and fails the large one.

Cleaning means opening the drain side, so the parts that come off are the ones that leak afterwards. Which ones depends on the unit type.

On a wall unit, the drain pan and the hose clip. The pan slides on guide rails, and a few millimetres forward of the coil housing leaves a gap. Water rolls down the fins, past the pan lip, and out of the casing front. The hose clip at the wall spigot fails differently: not fully engaged, it wets one fixed point on the trunking every time water passes.

On a ceiling unit, the drain joint at the pan outlet. It comes apart so the tray can be flushed. Pushed back but not tightened, it leaks at the fitting before the water reaches the drain line. Seen from below through a soaked ceiling tile, that reads as a failed pan.

On older wall units, the trunking. A plastic drain elbow can crack with age. Water leaves the tray normally, escapes at the crack, runs inside the trunking, and drips out lower down. The visible drip sits below the fault.

A cassette or a concealed unit hangs above the ceiling, so its water has to be pushed uphill by a pump. Wall units drain downhill and generally have none. That pump brings its own reservoir, float and discharge hose, each failing differently.

The chamber silts up. Scale and algae coat the impeller over years, add friction, then lock it against the wall. The motor hums, the shaft stays still, and the tray fills. Water then spreads across the panel and seeps through its joints at more than one point.

The discharge hose is the second. It sits over the pump outlet, and hours of compressor vibration can work it partly off. That joint holds through a morning check and lets go after most of a day.

Dust is the third. Condensate mixes with airborne dust and sets into sludge inside the line. The grille can look clean while the line runs half closed. Near a factory floor or ongoing renovation, that buildup arrives before the next service.

If water is anywhere near wiring, kill the isolator. Short of that, a drain leak waits for an appointment without harm. Keep the unit idle while it waits, because cooling makes the water. Slide a tray under the drip and photograph it before anyone mops.

Then go slowly on the first quote. A new pan, a new pump, or opening the ceiling are the usual offers here. In most situations above, the part was working.

Ask for every joint to be inspected first, and hold the pricing until that is done. Pan seating, hose clip, outlet nut, pump cover. Each takes minutes. If a joint proves sound, the part is still there to replace afterwards.

Ask also whether the pump failed or simply stopped clearing. One that hums without turning has seized. One that runs while the tray overflows is losing to a blocked line, and swapping it changes nothing.