How Often Should You Service Your AC? Home vs Commercial Schedules

“Once a year” is the answer most people expect, and for a bedroom split with light use it is roughly right. For a gym unit running twelve hours a day it is badly wrong. This guide replaces the rule of thumb with a schedule you can actually apply, based on how the unit is used and what it is exposed to.

The variables that actually matter

Four factors decide service frequency, and they multiply rather than add.

Running hours. A bedroom unit running eight hours a night accumulates roughly 2,900 fan hours a year. A shop unit running twelve hours a day accumulates 4,400. Dust builds with airflow, so hours matter more than calendar age.

Dust load. Ground-floor flats facing a main road, units near construction, and units beside a kitchen exhaust all collect far more than a fourth-floor flat with closed windows.

Humidity. In the Mumbai metropolitan region, six months of high humidity encourages biological growth on coils. Coils that stay damp between cycles need more frequent attention.

Unit type. Window units clean faster and hold cooling longer. Cassette and ducted systems hide their filters above a ceiling, so they are often neglected until airflow collapses.

A schedule you can apply

Where two rows apply, take the shorter interval. A roadside ground-floor bedroom belongs on a six-month cycle, not twelve.

Why commercial units need a different approach entirely

A commercial installation is a fleet, not a unit. If a home AC fails, one room is uncomfortable. If four of eight office cassettes fail in June, work stops.

That changes the goal from “clean when dirty” to “never let a unit reach the point of failure in peak season”. In practice that means planned servicing outside operating hours, at a frequency set by load, plus a documented record per unit so recurring faults are visible.

This is the logic behind an Annual Maintenance Contract: a fixed number of visits per unit per year, scheduled in advance, with the same technician team each time. It also creates history. A unit serviced four times a year with the same team gets diagnosed faster on the fifth visit because someone remembers what changed.

Don’t wait for the calendar: the signs that need attention now

Regardless of schedule, service immediately if you notice:

• Reduced airflow at the louver compared with a month ago.
• A musty smell in the first minute of running.
• Water dripping or staining near the indoor unit.
• Ice on the coil or on the thin copper line.
• Longer run times for the same room temperature.
• Rattling or vibration from the outdoor unit.

Longer run times are the most overlooked. A dirty coil makes the compressor work harder for the same cooling, so electricity use climbs before comfort drops. If your bill rose sharply with no tariff change, airflow is the first place to look.

Filter cleaning is not servicing

Weekly or fortnightly filter rinsing is a user task, and it is worth doing — but it is not a substitute for service. Filters catch coarse dust. The fine fraction passes through and coats the coil and blower, which is where airflow is actually lost.

This is why a unit whose filters were always kept clean can still have a completely blocked blower wheel after three years. The symptom is the same as a refrigerant fault — weak, slightly cool air — and customers often assume the worst.

Think of filters as maintenance between services rather than maintenance instead of services. The service is what removes what the filters could not stop.

Building a schedule that survives real life

The practical approach: pick two fixed dates a year — before summer and after monsoon — and adjust from there based on how the unit behaves. In the Kalyan, Dombivli and Thane belt, May and October are the natural slots.

For a home, that is enough. For commercial premises, put the dates in a contract with visit counts per unit, a response time for breakdown calls, and a named contact on both sides. Include a clause for how additional units added mid-term are handled — fleets grow, and a contract that does not anticipate it creates arguments.

Finally, keep a one-line log per unit: date, service level, any parts changed, and the next due date. That log is worth more than any rule of thumb, because it is about your equipment rather than an average.