Quoted an overhaul on every unit: one blocked drain
The quote covered a full chemical overhaul on four units at once, with no fault named against any of them. Overhaul scope should follow what the coils look like, not how many units sit in the home.
By Team Snowflake | Reviewed 25 Jul 2026
Case summary
Daikin Wall-mounted10 years oldCondoBishan, Singapore
- Concern
- Four units overhauled as one package when only one was dripping, with nothing to show which of them needed the work.
- Found
- One choked drain line on the living room unit, plus ordinary dust loading on all four coils that a general service clears
- Key check
- Opened each front cover and checked fin depth by hand, then poured water through every drain line to find the one that backed up
- Result
- The wall stayed dry through the next month of afternoon running. Cooling was unchanged at all four vents, because it had never been the problem. Overhaul scope dropped to a drain clear and a routine service.
What we were told
Three units were cooling normally. The fourth had dripped water down the wall twice in recent weeks, always in the afternoon. A servicing crew came, looked at the dripping unit, and quoted a package covering all four for deep cleaning. Nothing was said about what the other three were doing wrong.
What we checked
We ran all four units together and let them settle before touching anything. Supply air felt cold at every vent, which already argued against coils choked deep enough to justify stripping them down. So the question narrowed to why one room kept seeing water. We opened each cover and worked through the drains one at a time.
Supply air was cold at all four vents. Coil fins carried a light grey dust film, not the packed layer that blocks heat exchange.
Water poured into the living room drain pan backed up and sat there. The other three drains ran clear straight through.
The choked line held a soft plug of dust and slime near the outlet. It cleared with a hand pump and flushed freely afterwards.
What we found
Dust and biofilm collect in the drain line the same way they collect on a coil, but they cause trouble much sooner. A coil can hold a season of dust and still cool. A drain line only needs a small plug before water finds the wall instead of the pipe. The dripping unit was telling us about its drain, not about its coil, and the other three had no symptom at all.
What fixed it
We cleared the blocked line, flushed all four drains, and gave every unit a general service: filters washed, drain pans wiped, blower wheels brushed, condenser fins rinsed. No unit came off the wall. We explained where the overhaul threshold actually sits. When fins stay dark after a normal clean, or supply air stays warm with airflow strong, that is when stripping the unit down earns its cost.
Outcome
The wall stayed dry through the next month of afternoon running. Cooling was unchanged at all four vents, because it had never been the problem. Overhaul scope dropped to a drain clear and a routine service.
What this case teaches us
Overhaul scope is set per unit, not per household
- A quote that treats every unit in the house the same has not looked at any of them closely.
- Water backing up in one room is a drainage symptom. It says nothing about how dirty the coils are.
- Ask which unit was measured and what the reading was. Bundled overhaul pricing usually hides that answer.
Questions this case answers
What does it mean when an aircon drips water but still blows cold?
Should every unit in the house be chemically overhauled at the same time?
How do I know if an overhaul is genuinely needed?
Can a choked drain pipe be cleared without taking the aircon off the wall?
Ready to get started?
Tell us what’s going on. Symptoms, setup, photos, anything we should know. We’ll assess and come back with the right next step.