Toshiba multi-split, one bedroom warm: seized expansion valve, not a leak
A Toshiba multi-split in a Bukit Timah condo kept losing cooling in one bedroom. The living room and the other bedroom, sharing the same outdoor unit, stayed completely normal. The homeowner assumed a fresh gas top-up was needed, or that the whole system was starting to fail.
By Team Snowflake | Reviewed 11 Jul 2026
Case summary
Toshiba Multi-split9 years oldCondoBukit Timah, Singapore
- Concern
- The homeowner worried the whole system needed another costly top-up, or that the outdoor unit itself was starting to fail.
- Previous advice
- Homeowner assumed the whole system needed another gas top-up, or that the last one had not been enough
- Found
- That bedroom's own expansion valve had seized partly closed, restricting flow to its coil only
- Key check
- Pressure was checked separately at each room's own line across repeat visits. The affected bedroom's line held steady with no drop over time, ruling out a leak, while the other rooms and the outdoor unit read normal throughout
- Result
- Cooling returned to the affected bedroom within minutes and has held steady since. No gas was added, and the outdoor unit and the other two rooms were never touched.
What we were told
One bedroom had been blowing progressively warmer air over several weeks. The living room and the second bedroom, sharing the same outdoor unit, cooled normally the whole time. Gas had been topped up once before. The homeowner assumed either another top-up was needed, or a wider system fault.
What we checked
Only one room was affected while the rest of the system ran fine. That pointed away from the shared outdoor unit from the start. We checked whether the affected bedroom was genuinely losing gas, or just not receiving enough of what was already there. We tested that room's own line separately from the other two rooms.
The living room and second bedroom, sharing the same outdoor unit, cooled normally throughout, ruling out a shared or outdoor-side fault.
Pressure at the affected bedroom's own line held steady across repeat checks, with no drop over time, pointing away from a leak.
Flow into that bedroom's coil stayed restricted even though the line held enough gas, pointing at a blockage rather than gas loss.
That bedroom's own expansion valve, the part metering gas into its coil, was found seized partly closed. The same valve on the other rooms' units still moved freely.
What we found
The gradual warming in that one bedroom came down to its own expansion valve slowly seizing partly closed. Each indoor unit on a multi-split meters its own gas flow through its own valve, so only that room's flow was ever restricted. Pressure held steady on repeat checks, meaning no gas was escaping, so the earlier top-up had never actually been the problem, it just could not reach the coil properly.
What fixed it
We replaced the seized expansion valve on that one indoor unit only. The outdoor unit and the other two indoor units, including their own valves, tested normally and needed no work. After fitting the new valve, we ran the system and confirmed gas was flowing properly into the bedroom's coil again, then checked all three rooms together to confirm the rest of the system was still unaffected.
Outcome
Cooling returned to the affected bedroom within minutes and has held steady since. No gas was added, and the outdoor unit and the other two rooms were never touched.
What this case teaches us
One warm room on a multi-split can be that room's own valve, not the whole system
- Each indoor unit on a multi-split has its own flow-control valve. If only one room loses cooling while the rest keep working, check that room's own valve before assuming a bigger system problem.
- A steady pressure reading across repeat checks usually rules out a leak. If the level is not dropping over time, the fault is more likely a stuck valve than an actual gas loss.
- Ask which room is actually affected before agreeing to a system-wide top-up. One warm room on an otherwise fine multi-split usually points to a fix in that room, not the whole unit.
Related reading
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