Ceiling unit dripping after service: drain left loose

The ceiling unit had no issues before the service visit, then started dripping within hours of the technician leaving. When a leak appears right after maintenance, the work itself is usually the cause, not a new fault arriving by coincidence on the same day.

By Team Snowflake | Updated 28 Jul 2026

Case summary

Mitsubishi Electric Ceiling14 years oldOfficeMuseum, Singapore

Concern: Worried the service company had damaged the ceiling unit's drain pan during cleaning.
Found: Drain connection at the unit outlet was left loose after quarterly service reassembly, allowing drain water to drip before reaching the drain line
Key check: Checked all drain connections at the unit outlet and found the joint was hand-loose, not seated and tightened
Result: The drip stopped the moment the joint was tightened. The ceiling unit kept running on its original drain pan, with no replacement parts, no ceiling work, and no further leaks.

What we were told

The unit was fine before the quarterly service. Within a few hours of the technician leaving, water started dripping onto the office carpet. The service company said the drain pan may have cracked during cleaning, and quoted for a pan replacement.

What we checked

A leak that shows up right after servicing points to something handled during that visit. We checked the drain path from the pan outlet first, before inspecting the pan itself.

The drain connection at the unit outlet was loose. Its nut was only hand-tight, with no real grip, so the joint had not been properly tightened after reassembly.
Water was dripping at that connection, where the fitting meets the pan outlet, not from the pan surface or any crack in the tray.
The pan itself was intact on close inspection. No cracks, warping, corrosion, or stress marks anywhere on the tray, including the corners and the outlet.
The drain line was clear. Water exited freely at the discharge point, so nothing downstream was blocking the flow.

What we found

During the quarterly service, the drain joint at the pan outlet was opened to allow cleaning. This is normal on ceiling units, since the joint must come apart so the tray can be flushed. On reassembly, the technician pushed the fitting back into place but did not tighten the nut. The fitting sat there with no grip. Once cooling resumed, water collected in the pan and ran toward the outlet. With the joint unsealed, it escaped at the connection before reaching the drain line. The ceiling unit sits above the false ceiling, so the drip fell onto the ceiling tile and soaked through. That made it look like a leaking pan, when the pan was completely sound.

What fixed it

The pan was not damaged. The leak came entirely from the loose joint left after reassembly. We reconnected the fitting, tightened the nut properly, and ran the unit on cooling for twenty minutes while watching the connection for any moisture. The joint stayed dry throughout, and the line drained freely. No parts were needed: no pan replacement, and no ceiling repair beyond the access panel. We suggested the office manager flag the reassembly with the service provider so it is noted for future visits.

Outcome

The drip stopped the moment the joint was tightened. The ceiling unit kept running on its original drain pan, with no replacement parts, no ceiling work, and no further leaks.

What this case teaches us

A drip right after a service points back to the service

Timing is the clue. A unit that was dry for months and drips hours after a visit was almost certainly disturbed during that visit.
Servicing a ceiling unit means opening the drain joint to flush the tray. If that joint is not retightened, water escapes there before reaching the drain line.
Check the connection before accepting a pan replacement quote. A loose joint costs nothing to fix; a new pan does not.

Questions this case answers

Ceiling unit dripping within hours of a service visit: coincidence?

Very unlikely. A unit dry for months that drips the same afternoon was almost certainly disturbed during that visit. At this Museum-area office the drain connection at the pan outlet was only hand-tight with no real grip, and water escaped at that fitting, not from the tray surface or any crack.

Does servicing a ceiling unit involve opening the drain?

On a ceiling unit it usually does, since the joint has to come apart so the tray can be flushed. That step is normal. The risk sits in reassembly. Pushed back into position without the nut tightened, the fitting has no seal, and water escapes at the connection before it ever reaches the drain line.

How do I tell an overflowing pan from a loose fitting?

Look at exactly where the water leaves. Close inspection found this pan intact: no cracks, warping, corrosion or stress marks, including at the corners and the outlet. The drain line was clear and water exited freely at the discharge point. Everything converged on the one connection nobody had tightened.

Water is soaking through the ceiling tile. Does that mean the pan is damaged?

Not necessarily. A ceiling unit sits above the false ceiling, so a drip from any point lands on the tile and soaks through, which reads as a leaking pan whatever the true source. Tightening the nut stopped it here, and a twenty-minute cooling run with the joint watched confirmed it stayed dry.

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