How do I know if my aircon has a gas leak?
The clearest signs of a refrigerant gas leak are cooling that weakens over weeks, frost or ice on the copper pipes or indoor coil, and a compressor that runs nonstop while the room stays warm. The gas circuit is sealed and never used up, so low gas means a leak. A top-up without a repair only delays the problem. Key takeaways
- Low gas always means a leak: refrigerant isn't consumed, so a system that needs regular top-ups is leaking.
- Frost is a warning sign: with too little gas, the indoor coil runs too cold, so moisture freezes on it.
- Finding the leak is the real job: we combine a gas check, electronic leak detectors and bubble tests.
- The fix has an order: repair, test the pipes for leaks, pump out air and moisture, then charge the correct amount of gas. In the video above, Uncle Eric tracks down a gas leak on a Daikin aircon and fixes it, rather than just adding more gas. For another filmed case, where we traced a leak to a worn flare joint in a cramped attic, read Daikin aircon gas leak fixed.
What are the signs of an aircon gas leak?
No single sign proves a leak, but several together make it very likely.
Sign | Why it happens | Could it be something else? |
|---|---|---|
Cooling fades over weeks | Less refrigerant carries less heat out of the room | Dirt, but a clean won't stop the decline |
Frost or ice on the pipes or coil | Too little gas makes the indoor coil run below freezing | A badly clogged coil can do this too |
Compressor never rests | The room never reaches the set temperature | Undersized unit, dirty outdoor coil |
Hissing or bubbling near the pipes | Gas escaping at a joint (watch: leaking noises from an aircon) | Normal refrigerant flow sounds |
Oily, dusty patch at a joint | Refrigerant carries compressor oil out with it | Rarely anything else |
Water dripping after the unit stops | Ice on the coil melts and overflows the drain tray | A blocked drain |
| Higher electricity bills | The compressor works longer for less cooling | Dirt, heavier use | To check the first two signs yourself before booking, follow our guide to checking your aircon gas yourself.
Where do aircons usually leak gas?
In jobs like this we usually find the leak in one of a few places:
- Flare joints, where the copper pipes connect to the indoor and outdoor units. A poorly made flare or an overtightened nut can crack over time.
- Service valves on the outdoor unit, at the valve body or the cap.
- The coil itself. Copper coils can develop pinhole leaks, especially in humid, salty or polluted air.
- Damaged pipes, for example copper that was flattened, kinked or rubbed through during installation or renovation. Leaks also happen on newer units. Several of our videos show gas leaks on aircons only a few years old, where the cause is often a flare joint that has loosened or was not made tightly.
How do technicians find an aircon gas leak?
Finding the leak is the real work, so we follow a set sequence.
- Measure first. With digital tools we check how the gas is performing while the aircon runs. If it shows the system is low on gas, we move on to finding the leak. If the readings are normal, gas is not the problem and we look elsewhere.
- Electronic leak detection. An infrared gas leak detector and our Habotest HT601B+ sniff for refrigerant around joints, valves and the coil (watch: Habotest HT601B+ review). If the detector finds the area, go to step 3.
- Bubble test. Leak-detection solution on a suspect joint foams where gas escapes, which pinpoints the exact spot.
- Recover the gas, repair and test. The remaining refrigerant is recovered or pumped down before the circuit is opened, never vented. After the joint is re-flared, the valve replaced or the pipe repaired, we test the pipes to make sure they no longer leak.
- Pump out air and moisture. A vacuum pump clears the pipes before any gas goes back in.
- Charge the correct amount of the refrigerant on the unit's nameplate, then check the cooling again. If step 1 shows your gas is low, message Luna on WhatsApp to arrange a leak check rather than another top-up.
Why topping up gas alone isn't a fix
A top-up without a repair only buys time, and it costs owners more over time.
- The gas leaks out again. Weeks or months later you are back to weak cooling and another top-up.
- Air and moisture get in once the gas runs out. When enough gas has escaped, or a top-up is done carelessly, air and moisture can enter the system and damage the compressor oil and parts from the inside.
- The compressor is under strain. Running low on gas makes it work harder and hotter, and a failed compressor is the most expensive repair an aircon can need.
- Refrigerants must never be mixed. R22 is an old refrigerant no longer used in new units and being phased out, R410A followed it, and most current inverter aircons use R32, which is mildly flammable. Each system takes only the refrigerant on its nameplate. Our gas top-up service starts with a gas check, and finding the leak is our separate infrared leak check. If the gas turns out to be fine, the S$165 goes towards the service that fixes the cooling, and our guide to why an aircon is not cold covers the other usual suspects.
What it costs
Job | Price | What drives it |
|---|---|---|
Gas leak detection | S$580 (1 to 3 units), S$880 (4 to 5 units) | Number of indoor units |
Flare joint re-flare and recharge | Quoted after the leak check | Indoor or outdoor joint, ledge access |
Service valve repair or replacement | Quoted after the leak check | Brand, part availability |
Coil repair or replacement | Quoted after the leak check | Indoor or outdoor coil, model |
Evacuation and full recharge | Quoted after the leak check | Refrigerant type, pipe length, System 1 to 4 |
| Gas check and top-up (no leak found) | S$165 | Flat price for R32, R410A or R22 | The final cost depends on where the leak is and what has to be replaced.
When to call a technician
Get the system checked if:
- cooling has faded over several weeks, even after a clean
- you see frost or ice on the pipes or the coil
- you have needed more than one gas top-up in the past year or two
- you hear hissing near the pipes or the indoor unit
- the outdoor unit runs constantly but the room stays warm Gas leak repairs come under our aircon repair and troubleshooting service, with a repair warranty from 180 days (servicing carries 90 days). You can book online in under a minute, or ask Luna, our AI assistant, on WhatsApp 24/7.
Frequently asked questions
Is aircon refrigerant gas dangerous to breathe in at home?
A slow leak from a home split aircon releases a small amount of gas that disperses quickly, so it is not usually a breathing hazard in a ventilated room. R32, used in most newer aircons, is mildly flammable: if you suspect a leak, open a window, keep flames and sparks away and switch the unit off. A large leak in a small closed room can displace oxygen, so get it repaired promptly.
Can a new aircon have a gas leak?
Yes. We regularly find leaks on aircons only a few years old, often at the flare joints made during installation or at the service valves on the outdoor unit. A leak on a newer unit is usually an installation or joint issue rather than wear.
How long does it take to find and fix an aircon gas leak?
It depends on where the leak is. A leak at an accessible flare joint or service valve can often be found and repaired in one visit. A leak inside a coil or in piping hidden in trunking or a false ceiling can take longer and may need parts replaced.
Does aircon gas need to be topped up every year?
No. A sealed system that is not leaking keeps its gas for its whole life. If someone tells you your aircon needs a gas top-up every year, there is a leak that should be found and fixed instead.
Will the leak come back after it is repaired?
A properly repaired joint or replaced part should not leak again. A new leak elsewhere is possible on an older system, especially a corroded coil, which is why the whole system should be tested for leaks after the repair, not just the joint that was fixed.
Eric Lim, aka Uncle EricFounder of iAircon.Repair, now in its 10th year servicing aircons in Singapore. Every job is filmed, so you can watch the work on YouTube.
