Fujitsu · Heat pump

21 Address / refrigerant circuit setting error

Medium severity 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)

What the control is telling you

Unit number or refrigerant circuit address is set wrong (simultaneous multi / VRF). Indoor lamps: OPERATION (green) flashes 2x, TIMER (orange) flashes 1x, ECONOMY (green) flashes fast nonstop; wired remote shows 21.

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

Wrong rotary/DIP address
Duplicate address

Test and repair steps

Check address switches on each unit against the system plan.
Correct, then cycle power to all units.

Settings for these units

Operating range and service space · Fujitsu multi-zone outdoor 18/24 type

Other codes on the same units

14 Network communication error
15 Check run unfinished / airflow auto-adjust error
16 Peripheral unit / transmission PCB connection error
18 External communication error (WLAN / option adapter)
22 Indoor unit capacity error
23 Combination error
24 Connection unit number error
26 Indoor unit address setting 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.