Daikin · Heat pumps · Daikin Altherma 3 R F (split heat pump, R32)
F6-00OU: Abnormal high pressure in cooling
Name in the manufacturer's documentation (service manual): OU: Abnormal high pressure in cooling
[1]
In plain words (editorial)
Abnormally high pressure in cooling mode. The manual names a dirty outdoor heat exchanger first, then refrigerant circuit problems and faulty components.
When to call a service technician: Keep the outdoor unit's heat exchanger clean; if the code repeats, contact your installer.
✎ editorial – written from the cited sources, not a manufacturer statement. Status: draft.
For technicians
Possible causes (source text)
- Dirty outdoor heat exchanger[2]
- Closed stop valve in the refrigerant circuit[3]
- Faulty heat exchanger thermistor[4]
- Faulty expansion valve[5]
- Faulty main pcb[6]
- Non‑condensables and/or humidity in the refrigerant circuit[7]
- Clogged refrigerant circuit[8]
- Faulty 4‑way valve[9]
- Faulty refrigerant side thermistor(s)[10]
Steps given by the manufacturer (source text)
- Clean the outdoor heat exchanger[11]
- Check that all stop valves of the refrigerant circuit are open[12]
- Perform a check of the heat exchanger thermistor[13]
- Perform a check of the expansion valve[14]
- Perform a check of the main pcb[15]
- Check for the presence of non‑condensables and/or humidity in the refrigerant circuit[16]
- Check if the refrigerant circuit is clogged[17]
- Perform a check of the 4‑way valve[18]
- Perform a check of all refrigerant side thermistors[19]
⚠ Work on refrigerant circuits, mains electricity and PV DC wiring is for qualified technicians only.
The Polish page has more detail (plain-language explanation, safe checks, guides): Read in Polish →
Sources
Every statement has a footnote to the document and PDF page. “Quote verified” means the quote was found automatically in the text of that page.
- [1] Daikin Altherma 3 R F – ERGA04~08E + EHVH/X04+08S18+23E – Installer reference guide (4P629086-1D (2024.04)) , p. 254 official manufacturer document quote verified
F6-00 OU: Abnormal high pressure in cooling
- [2] Daikin – Service manual Daikin Altherma 3 R F + W, ESIE20-13C – 2022.09 (PDF copy on installer site cncpompyciepla.pl) (ESIE20-13C) , p. 45 manufacturer document – copy from a distributor quote verified
dirty outdoor heat exchanger.
- [3] Daikin – Service manual Daikin Altherma 3 R F + W, ESIE20-13C – 2022.09 (PDF copy on installer site cncpompyciepla.pl) (ESIE20-13C) , p. 45 manufacturer document – copy from a distributor quote verified
closed stop valve in the refrigerant circuit.
- [4] Daikin – Service manual Daikin Altherma 3 R F + W, ESIE20-13C – 2022.09 (PDF copy on installer site cncpompyciepla.pl) (ESIE20-13C) , p. 45 manufacturer document – copy from a distributor quote verified
faulty heat exchanger thermistor.
- [5] Daikin – Service manual Daikin Altherma 3 R F + W, ESIE20-13C – 2022.09 (PDF copy on installer site cncpompyciepla.pl) (ESIE20-13C) , p. 45 manufacturer document – copy from a distributor quote verified
faulty expansion valve.
- [6] Daikin – Service manual Daikin Altherma 3 R F + W, ESIE20-13C – 2022.09 (PDF copy on installer site cncpompyciepla.pl) (ESIE20-13C) , p. 45 manufacturer document – copy from a distributor quote verified
faulty main pcb.
- [7] Daikin – Service manual Daikin Altherma 3 R F + W, ESIE20-13C – 2022.09 (PDF copy on installer site cncpompyciepla.pl) (ESIE20-13C) , p. 45 manufacturer document – copy from a distributor quote verified
non‑condensables and/or humidity in the refrigerant circuit.
- [8] Daikin – Service manual Daikin Altherma 3 R F + W, ESIE20-13C – 2022.09 (PDF copy on installer site cncpompyciepla.pl) (ESIE20-13C) , p. 45 manufacturer document – copy from a distributor quote verified
clogged refrigerant circuit.
- [9] Daikin – Service manual Daikin Altherma 3 R F + W, ESIE20-13C – 2022.09 (PDF copy on installer site cncpompyciepla.pl) (ESIE20-13C) , p. 45 manufacturer document – copy from a distributor quote verified
faulty 4‑way valve.
- [10] Daikin – Service manual Daikin Altherma 3 R F + W, ESIE20-13C – 2022.09 (PDF copy on installer site cncpompyciepla.pl) (ESIE20-13C) , p. 45 manufacturer document – copy from a distributor quote verified
faulty refrigerant side thermistor(s).
- [11] Daikin – Service manual Daikin Altherma 3 R F + W, ESIE20-13C – 2022.09 (PDF copy on installer site cncpompyciepla.pl) (ESIE20-13C) , p. 45 manufacturer document – copy from a distributor quote verified
clean the outdoor heat exchanger.
- [12] Daikin – Service manual Daikin Altherma 3 R F + W, ESIE20-13C – 2022.09 (PDF copy on installer site cncpompyciepla.pl) (ESIE20-13C) , p. 45 manufacturer document – copy from a distributor quote verified
check that all stop valves of the refrigerant circuit are open.
- [13] Daikin – Service manual Daikin Altherma 3 R F + W, ESIE20-13C – 2022.09 (PDF copy on installer site cncpompyciepla.pl) (ESIE20-13C) , p. 45 manufacturer document – copy from a distributor quote verified
perform a check of the heat exchanger thermistor.
- [14] Daikin – Service manual Daikin Altherma 3 R F + W, ESIE20-13C – 2022.09 (PDF copy on installer site cncpompyciepla.pl) (ESIE20-13C) , p. 45 manufacturer document – copy from a distributor quote verified
perform a check of the expansion valve.
- [15] Daikin – Service manual Daikin Altherma 3 R F + W, ESIE20-13C – 2022.09 (PDF copy on installer site cncpompyciepla.pl) (ESIE20-13C) , p. 45 manufacturer document – copy from a distributor quote verified
perform a check of the main pcb.
- [16] Daikin – Service manual Daikin Altherma 3 R F + W, ESIE20-13C – 2022.09 (PDF copy on installer site cncpompyciepla.pl) (ESIE20-13C) , p. 45 manufacturer document – copy from a distributor quote verified
check for the presence of non‑condensables and/or humidity in the refrigerant circuit.
- [17] Daikin – Service manual Daikin Altherma 3 R F + W, ESIE20-13C – 2022.09 (PDF copy on installer site cncpompyciepla.pl) (ESIE20-13C) , p. 45 manufacturer document – copy from a distributor quote verified
check if the refrigerant circuit is clogged.
- [18] Daikin – Service manual Daikin Altherma 3 R F + W, ESIE20-13C – 2022.09 (PDF copy on installer site cncpompyciepla.pl) (ESIE20-13C) , p. 45 manufacturer document – copy from a distributor quote verified
perform a check of the 4‑way valve.
- [19] Daikin – Service manual Daikin Altherma 3 R F + W, ESIE20-13C – 2022.09 (PDF copy on installer site cncpompyciepla.pl) (ESIE20-13C) , p. 45 manufacturer document – copy from a distributor quote verified
perform a check of all refrigerant side thermistors.