Gas Keeps Running Out: Pinhole Leak in Pipe Behind the Wall

Gas keeps running out and the leak is called unfindable. Whether that is true, or whether the search simply has not finished.

By Team Snowflake | Updated 24 Aug 2026

Teaching case based on recurring Snowflake service patterns; identifying details are combined.

How this presents

Refrigerant needing to be replaced repeatedly on a system whose pipework runs concealed within a bedroom wall. Accessible joints have been checked more than once and found sound. The loss is slow and consistent.

Setup: Panasonic Wall-mounted10-12 yearsCondoNewton
Misread as: An unfindable leak that will keep coming back regardless of what anyone does.
Check first: Whether every accessible joint has been individually isolated and tested

What else produces this

Eliminating the reachable parts properly is what makes the remaining answer credible rather than a guess. With outdoor connections, indoor connections and both service points holding under isolated test, the only unexamined length is the buried run. That conclusion is reached by exclusion, and it is only as strong as the exclusion was. Which is why the earlier tests matter a great deal more than they appear to at the time.

Repeated loss alongside sound accessible joints leaves only the one section nobody has been able to examine directly.
Each reachable connection holding pressure under isolated test removes it individually rather than collectively.
The concealed section failing to hold when isolated confirms the loss is inside the wall.
A pinhole rather than a joint failure explains a loss that is slow, steady and unchanged over time.

Why it happens

Copper buried in a wall can corrode from the outside where moisture reaches it. It can also fail at a defect that was present when it was installed. Either produces a pinhole rather than a joint failure, so the loss stays slow and does not accelerate the way an opening joint does. There is no way to see it, and no way to reach it without breaking into finished surfaces. That is why exclusion is the only method available here.

What resolution involves

A new run is routed rather than the wall opened, wherever a surface path or an alternative route exists. That is usually cheaper, faster and far less disruptive than chasing a pinhole through finished plaster, and it leaves pipework that can be inspected in future. Where the appearance of a surface run is genuinely unacceptable, opening the wall is a legitimate choice. It should be a choice, though, rather than the default nobody was offered an alternative to.

How to tell it worked

The new run isolated and held under pressure before anything is made good. Anything sealed into a wall or boxed in before it is proven becomes very expensive to revisit.

Before you approve a quote

By exclusion means the exclusion has to be thorough

Testing each accessible joint individually is what makes the concealed conclusion trustworthy.
A pinhole leaks slowly and steadily. An opening joint accelerates. The pattern distinguishes them.
Rerouting usually beats opening a wall. Compare both before agreeing to demolition.

Questions this case answers

Gas keeps running out weeks after every top-up: what is going on?

The system is losing refrigerant slowly, and the likely point is the concealed run in the wall rather than the accessible joints. Those joints have been tested sound, and a loss that stays slow and steady points at a pinhole rather than a joint that is opening up.

Can a refrigerant pipe leak inside a wall?

Yes. Copper buried in a wall can corrode where moisture reaches it, or fail at a defect that was present when it was installed. Either produces a pinhole rather than a joint failure, so the leak stays slow and is invisible from outside.

Why does cooling hold for a few weeks and then fade again?

Because the leak is a pinhole, which loses refrigerant slowly and steadily rather than accelerating. The charge stays acceptable for weeks before cooling drops below usable, and it repeats until the concealed section is found.

What should be tested before paying for another top-up?

Each accessible joint, isolated and tested individually. Where they all hold, the concealed section is isolated and tested on its own before another top-up is paid for.

Describe your situation

Tell us what’s going on. Symptoms, setup, photos, anything we should know. We’ll assess and come back with the right next step.

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