24 - Connection unit number error.
The official Fujitsu General table says code 24 is a connection unit number error, described for indoor secondary units in simultaneous multi systems and for indoor or branch units in multi-split systems.
Family context is taken from Fujitsu General's floor-mounted split-system product pages. Error-code mappings below are conservatively taken from an official Fujitsu General installation-manual error table for a floor-mounted indoor unit, so exact display behavior and applicability can vary by controller and connected system type.
Severity
High
Display
Officially shown through the indoor-unit error display pattern during operation; this code is tied to multi-unit system configuration rather than a simple single-unit user setting.
Support first?
Often not
Models in range
AGU9RLF, AGU12RLF, AGU15RLF
What to do first
Start with these checks
- 1Do not keep cycling the system if multiple units are affected
- 2Note which indoor units show the fault
- 3Arrange service for a configuration check
Likely causes
What usually sits behind this code
A connected indoor or branch unit number does not match the configured system layout
System addressing or connection assignment issue
Installation or commissioning mismatch in a multi-split arrangement
Contact support
Contact customer support if any of these apply
- !The system is a multi-split or simultaneous multi installation
- !More than one indoor unit is affected
- !Cooling or heating cannot be restored after a restart
- - The official wording is brief and points to a unit-number mismatch.
- - This is more likely to be an installation or addressing problem than a routine maintenance issue.
Related codes
Nearby codes in this family
Source notes
Source and scope
Source: Fujitsu General installation manual
Official error-code table snippet for a Fujitsu General floor-mounted indoor unit lists code 24 as a Connection unit number error, with multi-system notes.
Last reviewed: 2026-04-19
Use this as an official-first pointer, not a repair authorization. Exact troubleshooting steps and code visibility vary by model, controller, and system configuration.