Every Zone Went Warm Together: Branch Distributor Leak

Every zone on a ducted system went warm at once, with a pressure code showing. What that code does and does not tell you.

By Team Snowflake | Updated 24 Aug 2026

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

How this presents

A system shutting down on a fault code and cooling poorly before it does. The same code has appeared elsewhere on entirely different causes. Nothing about the controller or the wiring looks disturbed.

Setup: LG Ducted10-12 yearsIndustrialChoa Chu Kang
Misread as: A control board or sensor fault, since the code appeared on the controller.
Check first: What measurement the code is actually based on

What else produces this

Reading what the code actually measures is worth more than looking the code up. A code triggered by a pressure reading fires whenever that pressure leaves its range. The list of things that move it includes the charge, the airflow on both sides, a restriction anywhere in the circuit, and a genuine sensor fault. Treating the code as a location rather than a measurement is what produces replaced boards on systems that were simply leaking.

A code reporting a pressure outside range widens the search rather than narrowing it to one part.
Normal airflow on both sides removes the two easiest explanations for the reading.
A charge below what the system requires accounts for the pressure directly.
A distributor joint on the branch pipework found leaking explains the missing charge.

Why it happens

Control boards monitor a small number of readings and report when one goes out of range. A low pressure reading can come from a shortage of refrigerant, from restricted airflow, from a blocked coil or from a sensor that is lying. The board cannot tell which, and neither can the code. What the code does is narrow the field to causes that would move that particular reading, which is genuinely useful and is not the same as a diagnosis.

What resolution involves

Repairing the leaking joint and recharging the system correctly leaves the code with nothing to report. The habit worth building is to ask what a code measures before asking what it means. That question turns a long list of possible causes into a short one, and it prevents the common and expensive mistake of replacing the part that reported the problem.

How to tell it worked

The system run through a full cycle with the reading watched, rather than the code simply being cleared. A cleared code proves nothing until the measurement behind it has been seen to sit where it should.

Before you approve a quote

A code reports a measurement, not a location

Ask what the code measures before asking what it means. That converts a name into a short list.
The same code appears on very different faults, because several things move the same reading.
Clearing a code is not a repair. Watch the reading it was based on through a full cycle.

Questions this case answers

What does CH38 on an LG system actually mean?

It reports that a reading has gone outside its expected range, which is a real and useful piece of information. What it cannot do is say which of the several things that affect that reading has changed.

Why did every zone on our ducted system lose cooling at the same time?

Every zone lost cooling together because the fault sat at one point they all share: the branch distributor where a single joint was leaking. A code identifies the reading, and several different faults move the same reading: a pressure code can come from a shortage of refrigerant, a blocked coil, restricted airflow or a faulty sensor.

Low refrigerant error on a ducted system: is the outdoor unit the cause?

Rarely, and it is the expensive assumption to make. Here the cause was a leaking joint on the branch pipework, not the outdoor unit; the code only reported the low pressure, so replacing the unit would remove the report rather than the cause.

What does it mean if only one duct zone goes warm?

It points at that zone's own branch line rather than at anything shared; a leak confined to one branch drains that zone alone while the others keep cooling. Ask what the code measures, then work through the things that move that measurement in order of cost: airflow and cleanliness first, charge next, and electronics last.

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