Every zone went warm together: branch distributor leak, not the outdoor unit
CH38 on an LG system flags low refrigerant, and a shared fault like this often points to the outdoor unit. But this ducted office system in Choa Chu Kang had every zone fading at the same rate, a pattern that pointed somewhere else first.
By Team Snowflake | Reviewed 11 Jul 2026
Case summary
LG Ducted5 years oldIndustrialChoa Chu Kang, Singapore
- Concern
- Facility staff feared a major outdoor unit fault and were bracing for a large repair or full replacement quote.
- Previous advice
- Facility staff assumed a major fault inside the outdoor unit and expected a large repair or full replacement quote
- Found
- A slow leak at a joint on the branch distributor feeding the duct zones, with the outdoor unit itself testing normal throughout
- Key check
- Checked whether the even, all-zone pattern pointed at the outdoor unit or at a shared fitting downstream of it, then traced the leak to the branch distributor before any outdoor unit work was considered
- Result
- Cooling returned evenly across every zone within the same day. The CH38 error cleared and has not returned. No outdoor unit parts were replaced or quoted.
What we were told
Every duct zone in the office was fading at close to the same rate, not just one area. Cooling had gone from fine to barely there across the whole space in a short stretch. Facility staff expected a major fault in the outdoor unit.
What we checked
Every zone fading at the same pace pointed toward something shared, not a fault building in one duct run alone. On a system feeding several zones from one outdoor unit, that shared point can sit in the outdoor unit itself. It can also sit in the fitting that splits the line into each zone's branch. We checked the outdoor unit first, since that was the original fear.
Refrigerant readings confirmed a genuine loss, not a sensor fault or blocked outdoor fan.
The outdoor unit's fan, coil, and wiring all tested normal, with nothing pointing to a fault there.
Following the shared line downstream led to the branch distributor, where every zone's supply splits off from one point.
A bubble test found an active leak at one joint on that distributor, with every other joint clean and dry.
What we found
The leak sat at a joint on the branch distributor, the fitting that splits the single line from the outdoor unit into the separate runs feeding each duct zone. Every zone draws from that one shared point. A leak there lets refrigerant escape from all of them at close to the same pace, rather than draining just one zone's line. The outdoor unit itself was never short of anything to send out.
What fixed it
We resealed the leaking joint on the distributor and checked the fitting to confirm no other joint was letting gas out. The system was then recharged to the correct level and run across every zone to confirm even cooling had returned. We flagged the distributor for a closer look at future services, since one joint aging faster than its neighbours can mean the others are not far behind. No outdoor unit work was needed.
Outcome
Cooling returned evenly across every zone within the same day. The CH38 error cleared and has not returned. No outdoor unit parts were replaced or quoted.
What this case teaches us
When every zone fades together, check the shared distributor before the outdoor unit
- If every zone on a ducted system loses cooling at the same pace, look at a shared fitting first. On this kind of system, that fitting is the branch distributor, not the outdoor unit.
- A leak on just one zone's own line only drains that zone. When every zone fades at a similar rate, the fault sits somewhere they share.
- Before approving major outdoor unit work on an even, all-zone fault, ask whether the branch distributor has been checked first.
Related reading
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