🏠 HDB Aircon Guide

HDB Aircon Servicing Singapore: Costs, Schedule & Ledge Rules (2026)

What HDB aircon servicing costs by flat type, how often to book, who looks after the aircon ledge and which HDB rules apply.

HDB aircon servicing means cleaning and checking every indoor unit in your flat, plus the outdoor condenser on the aircon ledge, every three to four months if you use the aircon daily. At City Cooling, general servicing costs $35 for one unit and $70 for three units, which covers a typical 3-room or 4-room flat. Prices are subject to GST.

This guide covers what servicing costs by flat type, how often to book, who is responsible for the aircon ledge, which HDB rules apply, the problems we see most in HDB flats and what happens on the day. If you are putting in a new system rather than maintaining one, read our HDB aircon installation guide instead.

How much does HDB aircon servicing cost?

General servicing for an HDB flat costs $35 for one unit, $70 for three units and $85 for four units at City Cooling, subject to GST. Most 3-room and 4-room flats run a System 3 with three indoor units, so a full general service is $70. Chemical overhauls and annual contracts are priced separately, as shown below.

Flat type (typical setup)	Indoor units	General servicing	Chemical overhaul*	Contract, 3x a year	Contract, 4x a year
1 room cooled	1	$35	$130	n/a	n/a
2 rooms cooled	2	$55	$260	$155	$195
3-room or 4-room flat (System 3)	3	$70	$360	$185	$220
5-room or Executive flat (System 4)	4	$85	$480	$230	$275
5 indoor units	5	$100	$550	$280	$335

*Chemical overhaul prices apply to 9,000 and 12,000 BTU units. All prices are subject to GST. Prices as listed on our pricing page; check it for the latest figures.

General servicing includes indoor filter deep cleaning, evaporator coil cleaning, drainage pipe clearing, a gas level check, electrical parts testing and a 90-day workmanship warranty. There is no transport or call-out fee.

The outdoor condenser is priced on its own. General servicing includes a check of the condenser coil; a full condenser service costs $80 and a condenser chemical wash costs $120. A chemical wash of the indoor fan coil, without dismantling, costs $85 per unit. If cooling stays weak after servicing, a gas top-up costs $100 to $150 for R32 units. See the full aircon servicing price list for every service.

How often should you service an aircon in an HDB flat?

Service each HDB aircon unit every three to four months if you run it four to eight hours a day. Heavier use needs servicing every one to two months, and light use every six to eight months. Add a chemical wash every six to twelve months and a chemical overhaul about once a year, or sooner if you notice smells, leaks or weak cooling.

Daily use	General servicing	Deep cleaning
Under 4 hours	Every 6 to 8 months	Chemical wash every 12 months
4 to 8 hours	Every 3 to 4 months	Chemical wash every 6 to 12 months
Over 8 hours	Every 1 to 2 months	Chemical wash every 6 months; overhaul yearly

Book a service before the hottest months, March to May, so the units are clean when you need them most. If you service three or four times a year, a contract usually costs less: for a 3-unit flat, four contract visits cost $220 against $280 for four separate visits. Our guide on how often to service your aircon goes into more detail.

Who cleans the aircon ledge in an HDB flat, and is it part of servicing?

Safety first: never climb onto the aircon ledge or lean out of a window to reach the condenser. Leave anything on the ledge to a technician.

If your block received its Temporary Occupation Permit (TOP) on or after 1 May 2004, the aircon ledge is part of your flat’s strata area, so you as the flat owner are responsible for keeping it clean, according to a Ministry of National Development written answer in 2023. That arrangement does not apply to older blocks, so check with your Town Council if your flat was completed before May 2004.

Town Council rules, set out in HDB’s air-conditioner installation guidelines, say the ledge is for condensing units only. You must keep it clean and unobstructed, must not tamper with it, and must let HDB, the Town Council and government officers inspect it. HDB also carries out checks for loose objects on ledges that could fall.

During general servicing, we check the condenser coil on the ledge. A full condenser service ($80) cleans the outdoor unit itself, which matters on ledges where leaves, dust and bird droppings build up around it and restrict airflow. Condenser cleaning is a separate service from general servicing, so ask for it when you book.

Book a condenser service if you can see debris piled around the outdoor unit, birds nesting on the ledge, rust on the bracket, or the condenser rattling when it runs.

What HDB rules apply when your aircon is serviced?

HDB requires air-conditioner installation works to be carried out by a BCA-trained installer and makes you, the flat owner, responsible for maintaining your units so they do not cause a nuisance to neighbours. When your aircon is serviced, the rules that matter cover where the condenser sits, where water drains and who can work on the system.

Only a BCA-trained technician should handle refrigerant, wiring and the outdoor unit.
The aircon ledge is for the condensing unit only, which must sit on rubber padding. HDB caps each condensing unit at 80kg for 1-room to 5-room flats.
Condensate water must drain into a floor trap inside your flat, and pipe joints must be insulated so they do not drip.
All piping must run inside the flat, and the external wall must be kept free of stains at the owner’s cost.
If your aircon causes a nuisance, such as dripping onto the flat below, HDB can require you to stop using or remove it.

These come from HDB’s air-conditioner installation guidelines. Rules for new installations, such as submitting an installation report to HDB within 14 days, are covered in our HDB aircon installation rules guide. All City Cooling technicians are BCA-certified.

What are the most common HDB aircon problems?

These are the issues we see most often in HDB flats, what usually causes them and what to do next.

Water leaking from the indoor unit

A clogged drain line, a dirty coil or ice forming on a coil low on refrigerant are the usual causes. Clearing the drain line is part of general servicing. If the leak returns, read our aircon leaking water guide.

Weak or no cooling

Dirty filters and coils restrict airflow; low refrigerant or a failing compressor are less common causes. Start with general servicing and a gas level check. Our guide to aircon not cooling covers the other causes.

Rattling, buzzing or grinding noises

Loose fan blades, worn motor bearings or debris in the outdoor unit are the usual sources. Book a service soon, because small mechanical faults get worse and cost more to fix.

Musty smell or mould

Mould grows on damp coils, filters and drain trays in Singapore’s humidity. If general servicing does not clear the smell, a chemical wash or a chemical overhaul cleans the parts that a normal service cannot reach.

Higher electricity bills

Clogged filters and dirty coils make the compressor run longer to reach the same temperature. Regular servicing keeps the system running efficiently. For other ways to cut costs, see our guide to saving on your aircon electricity bill.

The circuit breaker keeps tripping

Treat this as a safety issue. Switch the aircon off at its isolator, do not keep resetting the breaker and call a technician. Faulty wiring, moisture in electrical parts or a failing compressor can cause it.

One room is cooler than the others

An undersized unit, blocked vents, strong afternoon sun on one side of the flat or an unbalanced multi-split system can all cause it. A technician can check each unit’s output and airflow during servicing.

Problems with the outdoor compressor on the ledge

Vibration, rust on the bracket and overheating in tight ledge spaces are common on HDB ledges. Get these checked early, because the outdoor unit serves every room on a System 3 or 4. Read more about aircon compressor problems.

What happens during an HDB aircon servicing visit?

A City Cooling general service follows the same steps for every unit in your flat: inspect, test, clean, check and test again. In most HDB flats the condenser is reached through the window beside the ledge or through the service yard, so please keep those areas clear before the visit.

Inspection of each indoor unit and the condenser for damage and wear.
Testing of airflow, refrigerant pressure, electrical connections and drainage.
Cleaning of filters and the evaporator coil, and a flush of the drain line.
A check of the condenser coil, motor bearings and fan.
A cooling performance test, with a short report on what we found and what, if anything, needs attention.

A general service takes about 30 to 45 minutes per unit. Before the technician arrives, clear the space under each indoor unit, keep pets in another room and make sure the outdoor unit or aircon ledge can be reached. Same-day slots are often available, first come, first served. Contract customers get a WhatsApp reminder before each scheduled visit.

What can you safely do yourself between services?

You can clean the filters and wipe the vents yourself between professional services. Anything involving refrigerant, wiring, the inside of the unit or the aircon ledge should be left to a technician.

Safe to do yourself

Clean the air filters every two to three weeks: switch off, remove, rinse or vacuum, and let them dry fully before refitting.
Wipe the vents and front panel with a damp cloth. Never spray water into the unit.
Watch for leaks, new noises or rooms that take longer to cool.

Leave to a technician

Refrigerant top-ups and anything involving gas lines.
Dismantling the indoor unit or cleaning internal coils.
Any work on the condenser or the aircon ledge.

Our comparison of DIY and professional aircon servicing explains where the line falls.

Frequently asked questions

How much does it cost to service all the aircons in a 4-room HDB flat?

Most 4-room flats have a System 3 with three indoor units. General servicing for three units costs $70 at City Cooling, subject to GST. A full service of the outdoor condenser is a separate $80.

Is the condenser on the aircon ledge included in general servicing?

General servicing includes a check of the condenser coil. A full condenser service costs $80 per condenser and a condenser chemical wash costs $120. Annual contracts do not include condenser service.

Who is responsible for cleaning the aircon ledge in an HDB flat?

For blocks that received their TOP on or after 1 May 2004, the ledge is part of your flat, so the flat owner is responsible for cleaning it. For older blocks, check with your Town Council.

How often should I service the aircon in my HDB flat?

Every three to four months if you use it daily for four to eight hours. Book a chemical wash or overhaul about once a year, or sooner if you notice smells, leaks or weak cooling.

Do I need a BCA-trained technician for aircon work in an HDB flat?

HDB requires air-conditioner installation works to be carried out by a BCA-trained installer. For servicing, choose a company whose technicians hold the same training, since they handle refrigerant, wiring and the outdoor unit.

What is the difference between general servicing and a chemical overhaul?

General servicing cleans filters, coils and the drain line while the unit stays mounted. A chemical overhaul dismantles the fan coil unit and soaks every component in a chemical bath. It costs $130 per unit for 9,000 to 12,000 BTU units.

How long does HDB aircon servicing take?

A general service takes about 30 to 45 minutes per unit, carried out by a BCA-certified technician who cleans and checks every unit.

Is there a warranty after servicing?

General servicing carries a 90-day workmanship warranty. Water leaking after a service or chemical overhaul is covered for three months.

Book HDB aircon servicing with City Cooling

Tell us your flat type and how many units you have, and we will confirm the price before we arrive. WhatsApp us at 9890 9677 or book an appointment. For servicing beyond HDB flats, see our main aircon servicing Singapore page.