LG CH38 in Toa Payoh: Joint Loosened During a Chemical Wash
An error code days after a chemical wash, on an older system. Reading the timing before concluding that age has caught up.
By Team Snowflake | Updated 24 Aug 2026
How this presents
A code appearing within days of a chemical wash, with cooling fading behind it. The unit had been running without complaint beforehand. What is unclear from the room is whether the wash caused this or whether the timing is coincidence.
- Setup
- LG Wall-mounted10-12 yearsHDBToa Payoh
- Misread as
- An older system finally failing, when the timing points somewhere much more specific.
- Check first
- The outdoor fan and the sensor, then the joints the wash had to open
What else produces this
Two facts have to sit together here. A pressure code does not by itself prove gas has gone anywhere, because an obstructed fan or a bad sensor reports the same low number on a full charge. And a wash that reached the coil had to break a connection to get there. Eliminate the two cheap alternatives, then ask which connection was opened.
An outdoor fan running freely with nothing obstructing it removes the first alternative.
A sensor that reports accurately under test eliminates the second alternative.
A bubble test failing at the joint nearest the coil, the one opened for access, names the leak.
Every other connection tight and free of corrosion. Age-related leaks do not confine themselves to one joint and leave the neighbours sound.
Why it happens
Access is the cause here, not age. Reaching a coil for a proper clean means breaking a refrigerant connection and remaking it afterwards, and a remade connection either seats correctly or passes gas slowly. The fitting shows no wear because wear was never involved. Age produces corrosion, and corrosion spreads across the fittings that share the same air. It does not select one joint and leave every neighbour sound. A hand that opened one joint would.
What resolution involves
Reseat the joint properly after cleaning the faces, then recharge to the correct level. What matters as much is the sweep afterwards: a wash that needed one connection opened usually meant others were handled to get there, and a hand that left one loose is worth checking against the rest. That sweep costs minutes and is the difference between a repair and a return visit.
How to tell it worked
Ask which joint. A repair that names a specific connection and a top-up that names nothing look identical on the day, and only the second one comes back.
Before you approve a quote
Work that opens a joint owns that joint afterwards
- A code appearing days after a wash is about the wash. Sealed systems do not fail to a schedule.
- A pressure code has more than one cause. Ask whether the fan and the sensor were cleared before the pipework.
- Ask which connection was opened for access, and whether it was checked before the visit ended.
Questions this case answers
Why did a gas error appear right after a chemical wash?
What else can trigger CH38 besides a leak?
What does losing refrigerant on an older unit usually mean?
What should be checked after any service that opens refrigerant joints?
Ready to get started?
Tell us what’s going on. Symptoms, setup, photos, anything we should know. We’ll assess and come back with the right next step.