Two bedrooms losing cooling together: pinhole coil leak

Two bedrooms kept losing cooling together, while the living room held. Repeated gas top-ups bought a few cold days, then both rooms went warm again. The owner feared the whole multi-room setup needed replacing, but the fault was much smaller and sat at one shared fitting.

By Team Snowflake | Updated 28 Jul 2026

Case summary

Panasonic Wall-mounted9 years oldHDBSembawang, Singapore

Concern: Worry was that the entire multi-room setup needed full replacement.
Found: Pin-hole leak at the distributor joint feeding both bedroom indoor coils
Key check: Combined pressure hold with targeted dye and bubble tracing along the shared distributor line serving both bedroom coils
Result: The targeted repair held the pressure retest. Steady cooling returned to both bedrooms, and the repeat top-up cycle stopped. No coil was replaced.

What we were told

Both bedrooms cooled well for a while after each top-up, then went warm again together. The living room stayed cooler than the bedrooms the whole time. The owner had paid for several top-ups already and wanted to know if the setup needed replacing.

What we checked

Two rooms fading together while the living room held pointed to whatever fed just those two coils, not a system-wide gas problem. We ran a pressure hold test first to confirm the system was actually losing gas, rather than topping it up blind. With leakage confirmed, we worked inward. The pipe joints at each indoor unit were checked with soap solution, since loose joints are a common leak point and quick to rule out. Those came back clean, so we followed the line further, adding UV dye at the service port and running the system under load to carry it through to the distributor joint feeding both bedroom coils.

Operating pressure sat below the expected range, confirming gas was leaking out.
The two bedrooms declined together while the living room held, pointing at whatever fed only those two coils.
Soap-solution checks at every indoor pipe joint stayed clean.
UV dye traced the leak to the distributor joint feeding both bedroom coils.

What we found

A pin-hole leak had opened at the distributor joint that splits refrigerant into separate lines for each bedroom coil. That fitting takes more stress than a straight run as the system cycles on and off, so over years a tiny crack can form and let gas seep out slowly. That explains the pattern. Both bedroom lines draw from that same joint, so a leak there drains both coils at the same pace. The living room runs on its own separate distributor branch, which is why it kept enough gas to stay cool.

What fixed it

We laid out two options. The first was a targeted repair at the confirmed distributor joint, resealing the pin-hole without touching either bedroom coil. The second was replacing the distributor fitting outright, more thorough but with more downtime to access it. The leak was a single point, and both bedroom coils showed no other damage. On that basis we recommended the targeted reseal, and noted that if the seal held a pressure retest, the system would run normally with no major part replaced.

Outcome

The targeted repair held the pressure retest. Steady cooling returned to both bedrooms, and the repeat top-up cycle stopped. No coil was replaced.

What this case teaches us

A repeating gas top-up means find the leak, not refill it

If cooling fades again weeks after a top-up, gas is leaking out somewhere. Refilling treats the symptom, not the cause.
Which rooms lose cooling, and which hold, narrows the search. Two bedrooms fading together pointed to one shared distributor joint, not the whole system.
A confirmed single leak point can often be sealed at the fitting itself. Ask whether a targeted repair fits before agreeing to replace the unit.

Questions this case answers

Two rooms lose cooling together while the rest stay cold: what does that point to?

Whatever feeds only those two rooms. In this Sembawang flat both bedrooms faded together after every refill while the living room held, and the living room runs off its own distributor branch. That split pointed straight at the distributor joint the two bedroom coils share, and UV dye confirmed a pin-hole leak there.

How is a refrigerant leak located without dismantling the aircon?

Usually, yes, working from the outside inward. A pressure hold test came first to confirm gas was actually escaping, then soap solution at every indoor pipe joint, which stayed clean. UV dye added at the service port and carried round under load did the rest, tracing the loss to the shared distributor joint.

Is a pin-hole leak repairable or does the coil need replacing?

A single confirmed point can often be sealed at the fitting itself. Both bedroom coils here showed no other damage, so a targeted reseal was recommended over replacing the distributor fitting outright, which meant more access work and downtime. The reseal held a pressure retest and steady cooling returned to both rooms with no coil replaced.

Why do distributor joints crack?

They carry more stress than a straight length of pipe. Refrigerant splits into separate lines at that fitting and it flexes with every on and off cycle, so a tiny crack can open across the years and seep slowly. That is also why a leak there drains both bedroom lines at the same pace rather than one before the other.

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