Quoted an Overhaul on Every Unit: One Blocked Drain

One unit drips and all four are quoted for an overhaul. What to establish before agreeing to work on the three that are fine.

By Team Snowflake | Updated 24 Aug 2026

Teaching case based on recurring Snowflake service patterns; identifying details are combined.

How this presents

Three units cooling normally and a fourth that has dripped water down the wall twice in recent weeks, always in the afternoon. A quote has arrived covering deep cleaning on all four, with nothing said about what the three healthy ones are doing wrong.

Setup: Daikin Wall-mounted7-9 yearsCondoBishan
Misread as: Four units all needing deep cleaning, because one of them dripped.
Check first: Whether supply air is cold at every vent, then each drain line poured through separately

What else produces this

Water and warm air are different complaints with different thresholds. A coil fouled enough to justify stripping a unit down announces itself in the supply air, and cold air at every vent argues against that on all four. A drain needs far less to fail: a coil can hold a season of dust and still cool, while a line only needs a small plug before water finds the wall.

Supply air cold at all four vents argues against coils choked enough to need stripping down.
A light grey dust film on the fins is not the packed layer that blocks heat exchange.
Water poured into one drain pan backing up, while the other three run clear, isolates the fault to one line.
A soft plug near the outlet that clears with a hand pump and flushes freely afterwards names the whole fault.

Why it happens

Dust and biofilm collect in a drain line the same way they collect on a coil, and they cause trouble far sooner. The tolerance is completely different: a coil carries a season of loading and still cools, where a line needs only a small obstruction before water backs up and finds the wall. A dripping unit is reporting on its drain. It says nothing at all about its coil.

What resolution involves

Clear the blocked line, flush all four, and give every unit a routine service: filters washed, pans wiped, blower wheels brushed, condenser fins rinsed. Nothing comes off the wall. Worth stating plainly at the same time is where the overhaul threshold sits, because it is a specific condition rather than an interval. Fins that stay dark after a normal clean, or supply air that stays warm while airflow is strong.

How to tell it worked

Water poured through every line, not just the one that dripped. A blockage that has formed in one drain is forming in the others on the same schedule, and the cheap moment to find them is while somebody is already there.

Before you approve a quote

A quote should name what each unit did to earn it

One unit with a symptom is evidence about one unit. Ask what the others showed.
A drain fails on far less loading than a coil does. Dripping while cooling well points at the line, not the fins.
The overhaul threshold is a condition, not an age: fins dark after a normal clean, or warm supply air with strong airflow.

Questions this case answers

What does it mean when an aircon drips water but still blows cold?

That the cold side is working and the water side is not. Cooling produces condensate whatever else is happening, so a unit can cool perfectly and still fail to get that water into the pipe. Dripping with cold air at the vent points at the drain path rather than at the coil.

Should every unit in the house be chemically overhauled at the same time?

Only if each of them shows a reason. Units in the same home foul at different rates depending on the room, the hours and the doors. A package price across four is convenient to sell and says nothing about what any single unit needs.

How do I know if an overhaul is genuinely needed?

By condition rather than by calendar. Fins that stay dark after a normal clean, or supply air that stays warm while airflow is still strong, are the two signs that brushing and rinsing have stopped reaching the deposit. Neither is about how long since the last visit.

Can a choked drain pipe be cleared without taking the aircon off the wall?

Usually, yes. A soft plug near the outlet clears with a hand pump and a flush, and the unit stays on the wall throughout. Taking a unit down to reach a drain is a much larger job than the blockage normally warrants.

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Tell us what’s going on. Symptoms, setup, photos, anything we should know. We’ll assess and come back with the right next step.

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