LG CH38 in Toa Payoh: joint loosened during a chemical wash
CH38 on an LG unit flags refrigerant pressure that has dropped below normal. Repeat occurrences usually mean an active leak. This bedroom unit had just been through a chemical wash. The homeowner wasn't sure if the wash was to blame, or if the unit was simply worn out.
By Team Snowflake | Reviewed 11 Jul 2026
Case summary
LG Wall-mounted14 years oldHDBToa Payoh, Singapore
- Concern
- The homeowner worried the wash itself had caused the fault, or that age alone was catching up with an older system.
- Previous advice
- Assumed the wash had damaged the unit, or that the failure was simply due to its age
- Found
- Refrigerant leak at a flare joint loosened during a recent chemical wash, not corrosion or unrelated age-related failure
- Key check
- Outdoor fan and pressure sensor tested clear first, since either can trigger the same code. The joint opened during the recent chemical wash was then checked and failed a bubble test
- Result
- Cooling was restored and the CH38 error cleared. No parts were replaced and the leak has not returned. The wash itself was not at fault, and neither was the unit's age.
What we were told
A chemical wash had been done on this bedroom unit a few weeks earlier by a different contractor. Within days, the CH38 code appeared and cooling started fading. The homeowner wanted to know if the wash had caused the fault, or if it was just an older system giving out.
What we checked
A gas code appearing so soon after a wash pointed toward that visit. CH38 can also come from a blocked outdoor fan or a faulty sensor, so those were ruled out first rather than assumed. With both clear, attention turned to the pipework the previous contractor had opened to reach the coil for cleaning.
The outdoor fan ran freely with nothing blocking airflow, ruling out that as the trigger for the code.
The pressure sensor read correctly when tested on its own, so a faulty sensor was ruled out too.
The joint nearest the coil, opened during the wash to reach it, failed a bubble test with a slow, steady leak.
Every other connection on the unit was tight and free of corrosion, which ruled out a years-long age-related leak.
What we found
During the wash, the technician had to loosen a flare joint near the coil to get full access for cleaning, then reconnect it afterward. That joint was never fully retightened, and a slow leak began from that exact point. The fitting itself showed no wear or corrosion. This was not a years-long process, and it was not unrelated old-age failure either. It was a direct result of that one visit.
What fixed it
The fix was straightforward once the joint was identified. The connection was opened, cleaned, and properly reseated, then the system was recharged to the correct level. We also checked every other joint on the unit that was reachable during that same visit. A wash that requires opening one connection to reach the coil often means nearby fittings were handled too, so it was worth confirming they were seated properly.
Outcome
Cooling was restored and the CH38 error cleared. No parts were replaced and the leak has not returned. The wash itself was not at fault, and neither was the unit's age.
What this case teaches us
A gas error soon after a service points to a joint, not the wash or the unit's age
- A gas error within days or weeks of a service is the first place to look, not the unit's age. This includes any visit that opens refrigerant joints, such as a chemical wash or coil access.
- Ask whether every joint opened during that visit was checked for a tight seal afterward, not just reconnected.
- A service that disturbs a joint has not necessarily damaged the unit. The fix is usually reseating that one connection, not replacing parts.
Related reading
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