Signs Your Aircon Is Low on Gas (And What to Do)

We often see homeowners puzzled when their once-freezing units suddenly lose their chill.

A drop in cooling power usually points straight to a loss of refrigerant. This sealed system does not burn fuel like a car, so gas should never deplete under normal conditions.

Our team at Billy Aircon has grown from five to 26 members since 2003, and we handle these exact aircon servicing Singapore calls daily. So, I will break down the signs your aircon is low on gas and walk through the exact steps to fix it.

Signs Your Aircon Gas Is Low

Warm or Lukewarm Air

The most obvious indicator is a fan coil unit blowing air that is barely cool. Your aircon is running, but the room takes much longer to cool down or never reaches the set temperature.

We highly recommend looking for these specific temperature warning signs:

The air from the vent does not feel crisp.
A standard 9,000 BTU unit takes more than 15 minutes to cool an HDB bedroom.
A digital thermometer shows output air hovering above 18 degrees Celsius.
The room never fully reaches the temperature set on your remote.

If you notice these delays, the cooling capacity is severely compromised.

Ice on Copper Pipes

When gas pressure drops, the evaporator coil gets too cold and freezes the condensation from Singapore’s humid air. Thick ice eventually forms on the copper pipes connecting the indoor and outdoor units.

We frequently spot this icy buildup during routine maintenance checks. This solid block of ice will eventually melt and overwhelm the drainage pan. Water then overflows, potentially ruining your plasterboard ceilings or parquet flooring.

Ice forming on aircon copper pipes due to low refrigerant gas pressure

Hissing Sounds

You might hear distinct noises coming from the fan coil unit when things go wrong. A sharp hissing noise usually indicates pressurised refrigerant escaping through a tiny crack in the copper lines.

“A quick rule of thumb for homeowners: hissing means escaping gas under pressure, while gurgling means trapped water in your drainage pipe.”

Our repair teams always advise clients to listen closely to distinguish between these two issues. Ignoring a persistent hiss means the leak will only grow larger over time. Read our full guide on aircon gas leak signs for a detailed breakdown of what to look for.

Compressor Running Constantly

The compressor keeps running non-stop because the system cannot reach your desired thermostat setting. This continuous strain drastically reduces the lifespan of this crucial component.

We have seen overworked compressors burn out completely within just a few seasons. Replacing an aircon compressor in Singapore currently costs between SGD 600 and SGD 1,200, depending on the brand. You are far better off fixing a minor gas leak early before total failure occurs.

Higher Electricity Bills

Your system works overtime trying to cool the room, consuming 20% to 30% more electricity in the process. This spike hits hard with the current 2026 SP Group electricity tariff sitting at 29.11 cents per kWh.

A heavily used, gas-starved unit can easily add $30 to $50 to your monthly utility bill in Singapore.

Our energy audits consistently prove that a properly charged system pays for itself in power savings. Catching the inefficiency early keeps your household expenses manageable.

What to Do

You must never simply top up the gas without checking for leaks first. A properly installed system should retain its charge indefinitely.

We strongly warn against quick-fix top-ups because the new gas will just escape again. If your levels are low, there is a physical leak that needs fixing immediately.

Call a Technician for a Pressure Test

Professionals use a manifold gauge set to measure the exact suction and discharge pressures. This diagnostic tool connects directly to your outdoor condenser unit to read the system levels.

Our technicians typically look for a specific healthy suction pressure range based on your gas type. If the dial shows a severe drop, a leak is absolutely present and requires attention.

Find and Fix the Leak

Technicians will apply a specialised soap solution or use electronic leak detectors along the copper piping. Bubbles will form instantly at the exact site of the crack or loose flare joint.

Our repair teams focus on four main leak repair methods:

Re-flaring the loose copper connections.
Replacing the damaged pipe section entirely.
Tightening the service valves at the outdoor condenser.
Applying commercial-grade sealants for minor joint leaks.

This thorough process ensures the system is sealed tight before any new refrigerant is added.

Recharge with the Correct Gas Type

Your unit requires a specific refrigerant to function safely and efficiently. The National Environment Agency (NEA) enforces strict regulations regarding these gases, especially with the complete phase-out of R22 and the recent ban on new high-GWP equipment sales.

Our service fleet carries the modern R410A and R32 refrigerants, which are highly efficient and climate-friendly. Using the wrong gas type can cause catastrophic compressor failure. Making the right choice for your air conditioning system impacts both your wallet and your comfort.

We always encourage homeowners to look at the total cost of ownership rather than just the immediate price tag. Here is a clear breakdown of typical repair paths and their long-term consequences in Singapore. The data speaks for itself when comparing temporary fixes to permanent solutions.

Action	Estimated Cost in Singapore	Long-Term Result
Blind Gas Top-Up (No leak fix)	$50 - $80	Temporary fix, gas will leak again rapidly
Proper Leak Repair & Top-Up	$150 - $300	Permanent solution, restores cooling efficiency
Compressor Replacement (Neglect)	SGD 600 - SGD 1,200	Expensive overhaul, requires significant downtime

Technician measuring aircon gas pressure with manifold gauges before top-up