Aircon Not Cold? 9 Causes & What Each Fix Costs (Singapore 2026)

It is 2.30pm, 33°C outside, the aircon has run for an hour and the room still feels like a void deck. Before paying anyone: most "aircon not cold" cases in Singapore trace back to one of nine causes, and the first four cost nothing to rule out yourself. This guide runs through them in order of likelihood — from a remote stuck in Dry mode to a failing compressor — with the symptom that identifies each cause and what the fix costs.

Start with these 5-minute checks (no tools, no cost)

Run these before booking anyone — settings and airflow problems account for a surprising share of call-outs, especially after someone else has touched the remote.

If the aircon cools properly after these checks, you are done — put a monthly reminder to wash the filter and see how often aircon servicing is actually needed. If not, work through the causes below.

The 9 causes: symptom → fix → what it costs

Every price in the FixMove column matches our published price pages; market rates elsewhere will vary. Causes are ordered roughly from most to least common.

Causes 1–4: settings, filters and airflow — fix these yourself first

Settings (cause 1) are embarrassing but common. Dry mode is the classic trap: it cools briefly, then idles once humidity falls, so the room drifts warm again.

A clogged filter (cause 2) starves the indoor coil of airflow, so cooling capacity drops and in bad cases the coil ices over. Washing filters is free; a general service from S$50 per system covers the filters, blower, drain pan and a performance check.

A blocked condenser (cause 3) is the outdoor half of the same problem. Its job is to dump the heat collected indoors; boxed in by laundry racks, caked in dust, or recirculating its own hot exhaust on a cramped condo ledge, the whole system loses capacity — worst on the hottest afternoons.

An iced coil (cause 4) has two parent causes: restricted airflow or low refrigerant. The giveaway sequence is airflow fading to nothing, ice on the copper pipes, then water dripping as the ice melts — which is why "not cold" and "leaking water" so often arrive together. Switch off, thaw completely, wash the filter and test again. If it re-ices with a clean filter, assume a gas problem. (Dripping without ice is a different fault — see the aircon leaking water guide.)

Cause 5: low refrigerant — the truth about "gas top-ups"

The single most useful fact in this guide: aircon gas does not get used up. Refrigerant — R32 in most newer Singapore systems, R410A in many units from the 2010s — circulates in a sealed copper loop, moving heat from your room to the outdoor unit. It is not fuel. A healthy system should still hold its full charge years after installation.

So when a company says the gas is "low again" every year, what they are really telling you is that the system has a leak nobody has fixed — typically at a flare joint, corroded pipe bend or valve. Topping up without repairing it means paying S$80–150 each round for gas that escapes again within months, while the compressor runs hot in between.

Gas leak symptoms to look for

• Cooling got gradually weaker over weeks or months, not overnight
• Ice forming on the copper pipes or indoor coil
• A faint hissing near the indoor unit or pipe joints
• Oily residue around pipe connections (refrigerant carries lubricating oil out with it)
• The larger insulated pipe at the outdoor unit no longer feels cold to the touch while cooling
• Electricity bill creeping up while comfort goes down

The right sequence is a leak and pressure check (from S$80), repair of the leak point, then a regas. FixMove's R32 top-up starts from S$80 with the full range at S$80–150 depending on gas type and how much is needed — the gas top-up cost page breaks down R32 vs R410A pricing and when a top-up is legitimate versus a red flag.

Cause 6: dirty coils — when a general service is not enough

Singapore's mix of dust, cooking aerosols and year-round humidity slowly coats the evaporator fins and blower wheel in a grey biofilm that a surface clean cannot remove. The unit still blows, but the air is only mildly cool even with a fresh filter, often with a sour smell on start-up or water dripping from a fouled drain pan.

That is chemical wash territory: the technician strips the unit, soaks the coil and blower in a cleaning agent, flushes the drain tray and pipe, and reassembles. FixMove chemical wash runs S$90–280 per unit depending on whether it is a clean in place or a full overhaul with the fan coil dismounted — the chemical wash cost page has the tier-by-tier breakdown. Rule of thumb: if a normal service and clean filter did not restore cold air, or it has been 1–2 years since the last deep clean, step up to the wash — full comparison in chemical wash vs general servicing.

Causes 7–8: capacitor and compressor faults

The capacitor (cause 7) is a small, cheap part that gives the outdoor fan and compressor motors their starting kick. Singapore's heat is hard on capacitors, and a weak one produces a distinctive pattern: the outdoor unit hums or clicks but does not start, or cooling works on cool mornings and fails on hot afternoons when the heat-soaked motor needs more starting torque. It is a quick fix once diagnosed — and one of the happier outcomes of a S$80 diagnostic visit.

The compressor (cause 8) is the heart of the system and its most expensive component. Total failure looks like: outdoor unit completely silent (or tripping the breaker on start), indoor unit blowing room-temperature air indefinitely. On a unit under warranty or under ~8 years old, replacement of the compressor can make sense; on an older system it usually does not — see the repair-or-replace section below. Either way, insist on a written diagnosis before authorising a four-figure repair.

Cause 9: the unit is simply too small for the room

If the aircon has never been quite cold enough — fine at 3am, hopeless at 3pm — no amount of servicing will fix it, because the problem is arithmetic. A west-facing room, a top-floor HDB flat under a heat-soaked roof, or a living room opened up during renovation can all outgrow the capacity installed. As rough general guidance:

These are indicative figures — glazing, floor level and occupancy all shift the number, so capacity should be confirmed during an installation survey. If undersizing is the real problem, the money is better spent on a right-sized replacement than repeated servicing: FixMove does install-only work from S$450 for System 1 (System 2 from S$850, System 3 from S$1,200) and supply-and-install packages from about S$850 for System 1, quoted in writing after a site check.

Aircon not cold right after servicing? Three usual explanations

Few things annoy a homeowner more than paying for a service and getting warm air the same evening. Check these in order:

1. Settings were knocked. Technicians run units in different modes while testing. Confirm Cool mode, 24–25°C, fan Auto, timers off — this resolves a large share of "worse after servicing" complaints in one minute.
2. The filter went back in wet. A filter refitted damp chokes airflow and can smell musty for a day. Pull it out, dry it fully, refit, retest.
3. The real fault was never the dirt. A general service cleans; it does not seal a refrigerant leak or revive a weak capacitor. If the unit was cooling poorly before the service and still is after, the diagnosis was incomplete — ask for a pressure check rather than another wash.

A reputable company should return to re-inspect recent work under its workmanship warranty — FixMove does, with the quote in writing first. For service intervals and what each visit should include, see how often should you service your aircon.

When does repair stop making sense?

A rough decision rule that serves Singapore households well:

• Under ~8 years old: repair almost always wins. Gas leaks, capacitors, fan motors and even coils are all economically fixable.
• 8–10 years old: judge by the quote. A S$80–150 regas after a leak repair is fine; a four-figure compressor job on a 9-year-old system is usually money towards a new unit instead.
• Over ~10 years, or compressor gone: replacement usually wins. Newer R32 inverter systems cost noticeably less to run, and you reset the warranty clock.

At that fork, get the diagnosis first (from S$80) and ask for both numbers — repair quote and replacement quote — side by side. The FixMove aircon hub covers servicing, repair, gas, chemical wash and installation in one place.

Related Reading

• Aircon Singapore — servicing, repair and installation hub
• Aircon Gas Top-Up Cost Singapore — R32 vs R410A pricing
• Aircon Chemical Wash Cost Singapore — tier-by-tier rates
• Aircon Leaking Water: Troubleshooting Guide
• How Often Should You Service Your Aircon?
• Chemical Wash vs General Servicing
• All FixMove guides

FAQ

Published: 9 July 2026 · Updated: 9 July 2026 · By FixMove Home Repair Team. References: NEA (25°C energy-saving guidance), Meteorological Service Singapore.