CH38 in one bedroom only: pinhole leak in that indoor coil

LG's CH38 code flags low refrigerant pressure, and repeated appearances usually mean a leak somewhere in the system. On this Yishun condo's multi-split, only one bedroom lost cooling while every other room ran normally, which pointed the search away from the shared outdoor unit.

By Team Snowflake | Updated 28 Jul 2026

Case summary

LG Multi-split8 years oldCondoYishun, Singapore

Concern: Either the whole outdoor system was failing, or an earlier top-up simply hadn't been enough gas.
Found: Pinhole leak in the affected bedroom's own indoor coil, unrelated to the outdoor unit or any joint
Key check: Confirmed the other rooms on the same outdoor unit stayed cold, then traced the affected bedroom's own dedicated line before finding the pinhole on the coil itself
Result: Cooling returned to that bedroom within minutes of the recharge, and it has held steady since. The CH38 code cleared, and the other two rooms were never touched.

What we were told

One bedroom kept blowing warm air and showing the CH38 code, while the living room and the other bedroom stayed cold as usual. The unit had been topped up once before. The homeowner assumed the whole outdoor system, shared across all three rooms, was starting to fail.

What we checked

Only one room losing cooling on a shared system usually points at that room's own line. It rarely means the shared outdoor unit itself is failing. We checked gas pressure at the affected bedroom first to confirm an active leak. From there we worked outward along that room's own dedicated line, before touching anything the other rooms shared.

Gas pressure at the bedroom unit read low, while the other two rooms measured normal pressure on their own lines.
The other two indoor units, running off the same shared outdoor unit, cooled normally throughout, which ruled out a shared fault.
Tracing the bedroom's own line back from the indoor unit found no leak at any joint, valve, or fitting along the run.
A closer check of the bedroom coil itself found a small pinhole low on one row, the source of the slow leak.

What we found

Each indoor unit on a multi-split runs its own separate line back to the outdoor unit, so a leak on one line only affects that room. A pinhole had opened directly in the bedroom coil itself, not at any joint or fitting, from ordinary long-term wear. It was slow and hard to spot, letting gas seep out gradually. That is why CH38 kept showing in that one room while the other two, each on their own line, kept cooling normally.

What fixed it

We isolated the section of coil with the pinhole and replaced just that part, rather than the whole indoor unit or the outdoor system. The rest of the bedroom coil, and both other indoor units, were sound and did not need touching. Once the new coil section was fitted, we recharged that room's line to the correct level and pressure-tested it on its own before closing the unit back up.

Outcome

Cooling returned to that bedroom within minutes of the recharge, and it has held steady since. The CH38 code cleared, and the other two rooms were never touched.

What this case teaches us

On a multi-split, one room's fault is usually that room's own line

Each indoor unit on a multi-split has its own line to the outdoor unit. If only one room stops cooling while the rest keep working, the fault usually sits on that room's line alone.
A leak does not always sit at a joint or fitting. It can open directly in the indoor coil itself, which makes it harder to trace.
Ask which room is affected before agreeing to any system-wide work. One warm room on a shared system usually points to a fix in that coil, not a bigger repair.

Questions this case answers

Can only one room lose cooling on a multi-split while the others stay cold?

Yes, because each indoor unit runs its own line back to the shared outdoor unit. In this Yishun condo one bedroom showed CH38 and low pressure while both other rooms measured normal on their own lines. That split pointed the search at the bedroom's line, not at the shared outdoor unit.

How do you find a refrigerant leak that is not at a joint?

You keep tracing past the obvious points. Every joint, valve and fitting along the bedroom's own run tested tight and dry. A closer look at the coil surface itself turned up a small pinhole low on one row, opened by ordinary long-term wear rather than by any fitting coming loose.

What happens if the whole system gets topped up instead?

Gas escapes through the same pinhole and the code comes back. A top-up treats the reading, not the hole. Isolating and replacing only the affected section of coil, then recharging that one line and pressure-testing it alone, kept the work inside the room that actually had the fault.

Can a pinhole leak be repaired without replacing the whole indoor unit?

It was in this case. The rest of that bedroom coil was sound, and both other indoor units were never opened. Only the section carrying the pinhole came out. Once the new section went in, the line was recharged to the correct level and tested on its own before the unit was closed up.

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