Should you get a pressure test to find an aircon gas leak?
We do not recommend it. A pressure test seals the aircon off, fills its pipes with nitrogen and leaves it for 2 to 3 days to see if the pressure drops. It shows that something leaks, not where, and a worn gauge can leak too. Infrared and ultrasonic detectors find the actual leak point in one visit.
Key takeaways
- Days without aircon: the system is sealed off and left for 2 to 3 days.
- It does not show where: a pressure drop says something leaks, not which joint or pipe.
- The gauge can be the leak: worn gauges and hoses lose pressure themselves, and you cannot tell which leaked.
- There is a better way: we find leaks with infrared and ultrasonic detectors and confirm the spot before quoting.
In the video above, Uncle Eric uses our ultrasonic leak detector, a tool we adopted early in Singapore to find gas leaks without a pressure test.
How does a pressure test work?
To pressure-test an existing aircon, the indoor units, the pipes and the outdoor unit are closed off into one sealed loop. The loop is filled with nitrogen at high pressure and gauges are connected. Then everyone waits, usually 2 to 3 days, to see whether the reading drops. A drop means something in the loop leaks.
Why we stopped using it
Gauges and hoses leak too. Unless brand-new high-pressure gauges are used, the gauge or its hose can lose pressure on its own. A drop could be the aircon or the test equipment, and the homeowner has no way to tell which.
It does not say where. Even a real drop only proves there is a leak somewhere in the loop. Finding it still needs a detector.
It is slow and costly. Isolating the system takes time, and the aircon is off for days. You pay for the labour and live without cooling while you wait.
The result is hard to check. A homeowner sees a number on a gauge and has to trust what they are told. When the verdict is "multiple leaks", the next step can be new piping or a whole new system. That is a lot of money to spend on a result you cannot check yourself.
For these reasons we stopped using pressure tests to find leaks many years ago and invested in leak detectors instead.
Pressure test vs leak detectors
| Pressure test | Infrared and ultrasonic detection |
|---|---|---|
Time to a result | 2 to 3 days | The same visit |
Aircon off for | The whole test | Only while we work |
Shows where the leak is | No | Yes, then confirmed with a bubble test |
Can you check the result | Hard: a gauge reading | Yes: we show you the spot |
Risk of a false result | Gauges and hoses can leak | Low: the leak point is seen directly |
The infrared detector picks up escaping gas at joints, valves and coils. The ultrasonic detector listens for the hiss of gas escaping that the ear cannot hear. Once a spot is found, a bubble test shows it to you. Then we quote the repair, before any work starts. That is our aircon gas leak repair. Not sure it is a leak? Ask Luna on WhatsApp.
Questions to ask before you pay for a pressure test
- Where exactly is the leak? If they cannot show you, a pressure test alone will not tell them.
- Are the gauges new? Worn gauges can leak on their own.
- How long will the aircon be off? Usually 2 to 3 days.
- What happens if the pressure drops? Ask how they will find the leak point, and what it will cost.
- Can I see the leak before I agree to new piping? You should be able to.
If you have already been told you need new pipes, read how to get a second opinion on a gas leak.
Why is a pressure test harder on multi-split homes?
Many homes have a System 2, 3 or 4, with one outdoor unit and pipes running to every room, often through trunking or a false ceiling. Sealing all of that off for days means every room is without cooling. A detector checks each joint while the rest of the home stays cool.
What it costs
Job | Price | What drives it |
|---|---|---|
S$165 | Book this first if you are not sure it is a leak | |
Infrared leak check, 1 to 3 units | S$580 | If the gas is fine, the balance after the work done is kept for future services |
Infrared leak check, 4 to 5 units | S$880 | Number of units and pipe runs |
Leak repair | Quoted before any work | Where the leak is and how easy it is to reach |
For a full breakdown, read what an aircon gas leak repair costs.
When to call a technician
Call us when the cooling fades again weeks after a top-up, when you have been told you need a pressure test, or when someone has quoted new piping without showing you the leak. For the warning signs, read aircon gas leak signs; if you are not sure gas is the problem at all, read why an aircon is not cold.
Frequently asked questions
How much does an aircon pressure test cost?
We do not offer pressure tests to find leaks, so we have no price for one. Our infrared leak check is S$580 for 1 to 3 units and S$880 for 4 to 5, and most customers start with the S$165 gas check and top-up.
Can a pressure test find exactly where the leak is?
No. It shows whether the closed-off system loses pressure, not where. Someone still has to find the spot, which is what the infrared and ultrasonic detectors do directly.
How long is the aircon off during a pressure test?
Usually 2 to 3 days, because the pipes are left sealed to see whether the pressure drops. With infrared and ultrasonic detection the aircon is checked in the same visit.
Do you pressure-test a new installation?
No. After installing, we pump all air and moisture out of the pipes, then watch a digital gauge: if anything leaks, it shows straight away instead of after days of waiting.
What if my leak is inside a wall or ceiling?
We check everything we can reach first: the outdoor unit, flare joints, valves and the indoor unit. If none of them leak, the leak is in the concealed pipes, and we explain the options before any opening is made.
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.
