All rooms on your System 4 suddenly not cooling? All indoor units showing the same error code?
The most likely cause is a refrigerant leak in the shared pipework. SACES carries out nitrogen pressure tests on System 4 and multi-split aircon systems to pinpoint the problem — quickly and accurately.
A System 4 is a multi-split aircon configuration. One outdoor compressor unit is connected to four separate indoor units, covering up to four rooms from a single system.
System 4 units are common in 5-room HDB flats, executive flats, larger condos, and small offices.
Because all indoor units share the same refrigerant circuit and pipework, a single leak in the pipe affects every room at once. This is why all four units stop cooling at the same time, not one by one.
A pressure test, also called a pipe pressure test or leak test, pressurises the refrigerant pipework with nitrogen gas to check whether the system holds pressure.
Nitrogen is used because it is inert, dry, and safe. It does not react with the pipe or compressor components, and it leaves no residue.
If the pressure drops during the test, there is a leak in the system. The technician identifies the location of the leak before any repair or refrigerant top-up is carried out.
A pressure test is the only reliable method for confirming a refrigerant leak and its location in a multi-split system. Without it, topping up the gas will only delay the problem.
You need a pressure test in any of these situations:
Technician identifies the system type (System 3, 4, or 5), checks the number of indoor units, and reviews accessible pipe runs.
The refrigerant pipework is pressurised with dry nitrogen gas to the manufacturer's specified test pressure, typically 30 to 42 bar depending on refrigerant type (R22, R410A, or R32).
The gauge is monitored over a set hold period. Stable pressure = no leak. Dropping pressure = leak detected.
If pressure drops, the technician uses leak detection equipment and soapy water technique to identify the exact location of the leak along the pipe run.
A report of the test result is provided, including the pressure reading, whether the system holds, and the recommended next step (repair, re-pipe, or refrigerant charge if clear).
If the system holds pressure, no leak is found. The technician proceeds to vacuum the system and recharge with refrigerant. Your System 4 is restored to full operation.
If the system fails, a leak is confirmed. The technician identifies the location and advises on repair options. This may include a pipe joint repair, section re-pipe, or in severe cases, a full pipe replacement.
No refrigerant is charged until the pipe system has been confirmed leak-free. Charging a leaking system wastes gas and does not fix the underlying problem.
Note: If a repair is carried out on the same visit following a confirmed leak, the pressure test fee may be offset against the repair charge. Ask us when booking.
We carry out pressure tests on all major multi-split aircon brands available in Singapore, including System 3, System 4, and System 5 configurations.
System 4 is the standard configuration in 5-room and executive HDB flats, and is common in larger condos. We carry out pressure tests island-wide and work within MCST requirements for building and compressor access.
Landed properties have longer pipe runs that span multiple floors, making leaks harder to trace. We test the full system and locate the source of any leak before repair work begins. System 4 and System 5 covered.
System 4 configurations are common in shophouses, offices, and F&B outlets. We pressure test all multi-split setups, including ceiling cassette and ducted, and provide a written result after every test.
SACES has been servicing aircon units across Singapore for over 30 years. Our technicians are licensed, experienced on all major brands, and assigned to your property consistently.
Real feedback from Singapore homeowners and businesses.
In a System 4 (or any multi-split system), all indoor units share the same refrigerant circuit and outdoor compressor. If there is a refrigerant leak in the shared pipework, the pressure drops across the whole system — and all units lose cooling at once. A pressure test confirms whether a leak is the cause and locates it.
A gas top up refills the refrigerant level. A pressure test checks whether the pipework can hold pressure – i.e., whether there is a leak. If your system has a leak, a gas top up is a temporary fix. The refrigerant will escape again. A pressure test finds the leak so it can be repaired properly before the gas is recharged.
Yes. Nitrogen makes up about 78% of the air we breathe. When used for pressure testing, it is introduced into the sealed pipework, not released into the room. There is no risk of fire, no odour, and no chemical residue. It is the industry-standard gas used for this procedure.
For a standard System 4, the pressurisation and hold typically takes 1 to 2 hours. If a leak is found and needs to be located, add another 30 to 60 minutes depending on the pipe run length and accessibility. Full repair and recharge on the same visit is possible in most cases.
Yes. We carry out pressure tests for System 3, System 4, and System 5 configurations. The procedure is the same, the number of zones and total pipe run length affects the time and pricing. Contact us with your system details before booking for an accurate quote.
Possibly. New installations require a pressure test and vacuum procedure before refrigerant is charged. If your installer skipped or shortened this step, low refrigerant pressure or pipe contamination could be the cause. We can inspect and pressure test new installations to confirm everything was done correctly.
In cases where the pipe damage is extensive or concealed in inaccessible locations (such as buried in screed or behind solid walls), a full pipe re-run may be the only viable option. We assess each situation on-site and give you the options: repair, partial re-pipe, or full re-pipe, with honest cost estimates for each. No pressure to commit on the spot.
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Registered Contractor Under SCAL Association
Block 3024 Ubi Rd 3,
#01-61 Industrial Estate,
Singapore 408652
Mon–Fri: 8:30am–5:30pm
Sat: 8:30am–12:00pm
Sun: Closed
