'Service every 3 months' is the line you'll hear from every aircon company. It's a useful default, but the truth is more nuanced. Here's how to think about your actual servicing schedule.
The default: every 3 months for residential
This works for households running aircons 4–6 hours a day in 2–3 rooms. Singapore's humidity (80%+ year-round) and dust load mean coils foul faster than in dry climates — quarterly servicing prevents the buildup that causes weak cooling, water leaks, and musty smells.
Heavy users: every 2 months
If your bedroom aircon runs 8+ hours nightly (most parents of young kids fall here), or you have multiple units running through the day, drop to bi-monthly servicing. The extra wear comes from longer run-times allowing more biofilm growth on the cold evaporator coil.
Light users: every 4–6 months
Holiday homes, single-occupant units used only in evenings, or aircons in study rooms running a few hours a week can stretch to 4–6 months between services. Don't go longer — refrigerant pressure should be checked twice a year regardless of use, and dust accumulates even when units aren't running.
Commercial: monthly minimum
Offices, retail, F&B, clinics — monthly servicing is the industry standard. Skipping it voids most warranties and shortens equipment life by 30–50%. F&B kitchens with grease in the air may need fortnightly cleaning of the indoor units that face the cooking area.
When to add chemical wash
Even with disciplined quarterly servicing, schedule a chemical wash every 12–24 months. Earlier if you notice: persistent musty smell from the unit, visible mould on vents, water dripping from the indoor unit, or cooling power weaker than 12 months ago.
Signs you waited too long
Aircon takes longer than 10 minutes to cool a room. Water dripping from indoor unit when running. Musty or sour smell when you turn it on. Visible black or yellow patches on the louvres. Electricity bill jumped without behaviour change. Tripping circuit breaker.
The cost equation
Quarterly servicing: about $400–$700/year for a typical 3-aircon HDB. Chemical wash every 18 months: about $300–$450 amortised yearly. Total maintenance budget: $700–$1,150/year. Compare to a $1,800–$2,800 replacement system you'd need 2–3 years sooner from neglect — the maintenance pays for itself.