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Fujitsu · Heat pump

A4 High pressure error

High 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

System high pressure too high. Indoor lamps: OPERATION (green) flashes 10x, TIMER (orange) flashes 4x, ECONOMY (green) flashes fast nonstop; wired remote shows A4.

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

  • Blocked outdoor coil / fan fault (cooling)
  • Indoor airflow low (heating)
  • Overcharge / non-condensables
  • Valves not fully open

Test and repair steps

  1. Make sure service valves are fully open.
  2. Check airflow on the condensing side.
  3. Check charge.
  4. Check the HP sensor/switch.

Settings for these units

Other codes on the same units

  • 97 Outdoor fan motor error
  • 98 Outdoor fan motor 2 error
  • 99 4-way valve error
  • A1 High discharge temperature
  • A3 High compressor temperature
  • A5 Low pressure error
  • J1 VRF branch box error
  • J2 Branch box error (flexible multi)

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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.