"Every three months" is the number most people have heard, and it is not wrong so much as useless: it is a marketing-friendly average, not a reading off your specific unit. Two identical split units in the same building can need completely different service intervals depending on what is actually happening around them.
What actually determines the interval
Two things matter far more than the calendar.
- Dust exposure. A unit near an open window, a construction site, or a road with heavy traffic loads its filter and coil far faster than one in a sealed, high-floor apartment.
- Run hours. A Dubai AC often runs close to year-round rather than seasonally, so "months since last service" undercounts the real wear compared with a climate where it runs four months a year.
Signs it needs attention now, regardless of the calendar
- The room takes noticeably longer to cool than it used to, for the same thermostat setting.
- The electricity bill has crept up without a change in how the AC is used.
- A musty smell when it first switches on — usually biofilm building up in the drain pan or on the coil.
- Warm patches in a room that used to cool evenly.
A simple monthly check anyone can do
Pull the filter and hold it up to light — if you cannot see light through it clearly, it needs cleaning. Listen for any change in the sound the unit makes on startup. Check that the drain line is actually dripping when the unit is running (a dry drain line on a running AC usually means a blockage, not that nothing is being removed from the air).
Beyond the filter, a proper service means reading the coil temperature split and the refrigerant pressures rather than guessing — see our AC maintenance and repair page for what a visit actually checks.
Ducted and chiller units follow the same logic
A blocked filter on a ducted or chiller unit is invisible until the room stops cooling properly.
The two things that matter most — dust exposure and run hours — apply just as much to a ducted system or a chiller fan coil unit as to a wall split. The difference is access: the filter and coil usually sit behind a ceiling grille rather than in plain sight, so the simple monthly check above is harder to do without removing a panel. That is the real reason these systems tend to go longer between inspections than a wall split does, not because they need less attention.
