HVACopediaFujitsu · Heat pump
24 Connection unit number error
What the control is telling you
Too many or wrong number of indoor units / branch units connected. Indoor lamps: OPERATION (green) flashes 2x, TIMER (orange) flashes 4x, ECONOMY (green) flashes fast nonstop; wired remote shows 24.
Applies to: Fujitsu ductless heat pumps: Fujitsu ductless split/multi/VRF (general code list), Fujitsu wall-mounted 7-15 (NA ASU/AOU type), Fujitsu slim duct ARU 7-18 (LL type)
Likely causes
- Unit count outside the allowed range
- Address setup wrong
Test and repair steps
- Count connected indoor and branch units and compare with the system limits.
- Check address settings and cycle power.
Settings for these units
- Operating range and service space · Fujitsu multi-zone outdoor 18/24 type
Other codes on the same units
- 18 External communication error (WLAN / option adapter)
- 21 Address / refrigerant circuit setting error
- 22 Indoor unit capacity error
- 23 Combination error
- 26 Indoor unit address setting error
- 27 Primary / secondary unit setup error
- 29 Connection unit number error (wired remote system)
- 31 Power supply interruption error
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Source: Fujitsu All Fujitsu split - multi - VRF (generic code list) codes.pdf - section error code table (indoor LED flashes); Fujitsu Wall-mounted 7-9-12-15 (North American trilingual, UTY-RNNUM remotes; e.g. ASU9-12-15 RLF1-RLS familie.pdf - section 14 Error codes; Fujitsu Slim duct AR07-09-12-14-18 (ARU-ARYG LL-type equivalent) installation P-N 9381858064.pdf - section 14 Error codes. Summarized in our own words; check the original manual for your model.
Homeowner looking at this code? See what it means for you and when to call a technician.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.