Bedroom leaked after servicing: drain joint left slightly loose

Water showed up the same evening after a routine service, and that timing was the clue. A leak that starts right after work points back to the drain path that was just taken apart and put together. We treated it as a workmanship follow-up, not a new hidden failure.

By Team Snowflake | Updated 28 Jul 2026

Case summary

Mitsubishi Electric Wall-mounted8 years oldHDBBukit Batok, Singapore

Concern: The worry was that the indoor drain tray had cracked during servicing and the whole fan coil needed opening up.
Found: Drain hose clip not fully engaged at the wall spigot after reassembly
Key check: Ran water through the drain tray and followed the hose along the wall trunking to the spigot connection
Result: The leak stopped on the same visit with no parts replaced. The unit ran long enough to confirm normal drainage. For the homeowner, the point was knowing this was not a second major fault, just a small reassembly slip that could be checked, corrected, and proven on the spot.

What we were told

The bedroom aircon was serviced in the afternoon. By night, water was dripping from the right side of the indoor unit. It had not leaked at all before the service.

What we checked

Because the leak began right after servicing, we checked the parts just removed and refitted before looking deeper. For a wall-mounted unit, that means the drain hose route down the wall, not just the indoor cover. The first flush ran with the trunking open so the spigot, hose clip, and wall outlet could all be watched.

Filter and front cover were fitted correctly.
Drain tray was intact with no visible crack.
Water poured into the tray escaped at the hose clip on the wall spigot.
The wall outlet further down the trunking stayed dry, so the leak was fixed to that one connection.

What we found

The hose clip at the wall spigot had not been fully engaged after cleaning. A little water escaped at that loose grip instead of continuing down through the trunking. The tray and the buried pipe run were both undamaged. The drip tracked to one exact point along the trunking every flush, not scattered marks from a cracked tray or a hidden choke further down. That fixed point tied the fault to the clip just reassembled, not to the tray or the buried pipe.

What fixed it

We reseated the hose clip firmly onto the wall spigot and flushed the tray again while watching that connection. Water ran cleanly down through the trunking with no further drip. We did not quote a tray replacement, because the tray held water once the clip was seated. We asked to run the unit normally that night and check along the trunking route, since a separate concealed leak would show again after longer cooling.

Outcome

The leak stopped on the same visit with no parts replaced. The unit ran long enough to confirm normal drainage. For the homeowner, the point was knowing this was not a second major fault, just a small reassembly slip that could be checked, corrected, and proven on the spot.

What this case teaches us

A leak that starts hours after servicing is usually a loose reassembly

Timing narrows the cause. This unit was dry before the service and dripping by night, so the parts just removed and refitted were checked first.
Watch where the water escapes before assuming the worst. Here it slipped out at the hose clip on the wall spigot, not a cracked tray, so no part was needed.
Note when the first drip appeared and where. That timeline keeps a post-service follow-up fair and separates it from an older choke deeper in the pipe.

Questions this case answers

Aircon started leaking the same night it was serviced. Why?

Timing is the clue. A bedroom unit that stayed dry for months and drips by evening points back to whatever was taken apart that day. We flushed the tray and followed the hose route down the wall trunking. Water escaped at the clip on the wall spigot, so the fault sat at the connection just reassembled.

Does a leak after cleaning mean the drain tray is cracked?

Not usually. This tray held water perfectly well once the clip was seated, and no crack showed anywhere on it. A cracked tray tends to leave scattered wet marks. The drip here landed at one fixed point along the trunking on every flush, which pinned the fault to a single joint.

How do I know whether the water is from the tray or the drain hose?

Watch where it actually escapes during a flush. We poured water into the tray with the trunking open, so the spigot, the clip and the wall outlet were all in view at once. The outlet lower down stayed dry, ruling out a choke deeper in the pipe. Only the clip leaked.

Can a loose drain connection be sorted without replacing parts?

Often yes. Reseating the clip firmly onto the wall spigot ended it on the same visit with nothing replaced. We flushed again and watched that joint while water ran down through the trunking. Running the unit normally overnight is the sensible follow-up, since a separate concealed leak would reappear after longer cooling.

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