Why can't anyone find my aircon gas leak?
When the gas keeps running low but every joint, valve and coil tests clean, the leak is usually inside the concealed copper pipes, in the wall, ceiling or trunking where no detector can reach. A very mild leak can be sealed from inside. A faster leak, or old pipes in poor condition, means new piping or a new system.
Key takeaways
- Low gas always means a leak: the gas circuit is sealed, so the gas is never used up.
- Check every point first: on a System 2 that is 15 possible leak points, indoors and outdoors.
- Clean points point to the pipes: if all of them pass, the leak is in the piping you cannot see.
- Two ways forward: a sealant for a very mild leak, or new piping or a new system for the rest.
In the video above, a System 2 kept losing gas. We went over every possible leak point with an ultrasonic leak detector and soap foam. None of them leaked. We did find a kinked copper pipe from poor earlier work, and the system was in very bad condition, so we advised new piping and a new system.
Which points does a proper leak check cover?
On this System 2 we checked 15 points:
Where | Points checked |
|---|---|
Indoor coils (evaporators) | 2 |
Flare nuts at the indoor units | 4 |
Flare nuts at the outdoor unit | 4 |
Service valves | 4 |
Outdoor coil (condenser) | 1 |
Total | 15, no leak found |
A full check covers every one of these with electronic detectors, not soap alone: the smallest leaks escape at so little pressure that soap never forms a bubble. If someone tells you to replace your piping, ask them to show you which points they checked and how, as we explain in get a second opinion before replacing aircon piping. A customer who had our ultrasonic test wrote in their review that it was quicker than the traditional way.
Gas running low again after a top-up? Book a gas check first, and we will tell you if a full leak check is needed.
What happens when no leak is found?
- Measure how fast the gas is lost. Cooling that fades slowly, over 5 to 8 months after a top-up, points to a very mild leak. Cooling that fades within weeks points to a bigger one.
- For a very mild leak: a leak sealant injection. A sealant goes in with the refrigerant and closes very small leaks from the inside. We use it only when the leak is very mild and cannot be found, never in place of a repair we can make.
- For a faster leak or poor pipes: new piping. The old concealed pipes are replaced, so there is nothing left to leak.
- For a system in poor condition: a new system. When the aircon itself is old or badly installed, as in the video, new piping alone is money spent on a unit near the end of its life. A new installation with new piping is the better choice.
Our tools for each step are in the aircon tools we use, and the signs to watch for are in aircon gas leak signs.
What it costs
Step | Price |
|---|---|
Gas check and top-up | S$165 |
Infrared leak check | S$580 for 1 to 3 units, S$880 for 4 to 5, gas top-up included |
Leak sealant injection | Advised on site, for very mild leaks only |
New piping or new system | Quoted per job; installation labour from S$500 |
Every repair is quoted before any work. See our gas leak repair service for how a found leak is fixed and refilled.
Frequently asked questions
Why can't the technician find my aircon gas leak?
Most leaks sit at a flare joint, a valve or a coil, where a detector can reach them. When all of those test clean, the leak is usually inside the copper pipes hidden in the wall, ceiling or trunking, where no detector can get close.
What is a leak sealant injection?
A sealant goes into the gas circuit with the refrigerant and seals very small leaks from the inside. We use it only for very mild leaks that cannot be found, not for a leak we can see and repair.
Do I need a whole new aircon if the leak is in the pipes?
Not always. New piping can fix a leak in old pipes. When the system itself is also in poor condition, as in this case, a new system with new piping is the better use of your money. We show you what we found and quote both.
Can a pressure test find a hidden pipe leak?
A pressure test can show that the system leaks, but not where. It takes days, and a worn gauge can leak too. We use infrared and ultrasonic detectors to test every point we can reach instead.
How much does the leak check cost?
Start with the gas check and top-up at S$165. If the gas keeps running low, the infrared leak check is S$580 for 1 to 3 units or S$880 for 4 to 5, with the gas top-up included.
Eric Lim, aka Uncle EricFounder of iAircon.Repair, now in its 10th year servicing aircons in Singapore. Some of our jobs are filmed, and you can watch the work on YouTube.
