HVACopediaFujitsu · Heat pump
31 Power supply interruption error
What the control is telling you
A power interruption was detected. Indoor lamps: OPERATION (green) flashes 3x, TIMER (orange) flashes 1x, ECONOMY (green) flashes fast nonstop; wired remote shows 31.
Applies to: Fujitsu ductless heat pumps: Fujitsu ductless split/multi/VRF (general code list), Fujitsu slim duct ARU 7-18 (LL type)
Likely causes
- Momentary power loss
- Loose supply connection
Test and repair steps
- Check supply connections and breaker.
- Ask about recent outages; reset and monitor.
Settings for these units
- Operating range and service space · Fujitsu multi-zone outdoor 18/24 type
Other codes on the same units
- 24 Connection unit number error
- 26 Indoor unit address setting error
- 27 Primary / secondary unit setup error
- 29 Connection unit number error (wired remote system)
- 32 Indoor main PCB error (EEPROM / model info)
- 33 Indoor fan motor power consumption error
- 35 MANUAL AUTO button error
- 39 Indoor fan motor power supply error
Save it for the next call
Star this code in the HVACopedia app and keep the whole library on your phone for jobs with no signal.
Source: Fujitsu All Fujitsu split - multi - VRF (generic code list) codes.pdf - section error code table (indoor LED flashes); 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.