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Viessmann · Mini-split

F1 Outdoor ambient sensor (T4) fault

Medium severity Viessmann Vitocal 200-S DLCM(R/H)B multi-zone outdoor

What the control is telling you

Same fault as EC53. Shown on the 48K high heat model.

Applies to: DLCMHBH48EAK (48K high heat) only

Test and repair steps

  1. Safety kill power at the disconnect and wait for the inverter capacitors to discharge before touching boards or wiring.
  2. Check the sensor plug on the board and the wire for damage.
  3. Unplug the sensor and measure its resistance. T1-T4 sensors read about 10 kOhm at 77 F (25 C); the discharge sensor (T5/TP) about 54.9 kOhm at 77 F. Compare with the sensor resistance tables.
  4. Out of range or open/shorted replace the sensor. Sensor reads fine: replace the board it plugs into.

Models that show this code

7 models in Viessmann Vitocal 200-S DLCM(R/H)B multi-zone outdoor

DLCMHBH24CAKDLCMHBH30DAKDLCMHBH36DAKDLCMHBH48EAKDLCMRBH18BAKDLCMRBH36DAKDLCMRBH48EAK

Other codes on the same units

  • EL01 Indoor / outdoor communication error
  • F0 Current overload protection
  • F2 Condenser coil sensor (T3) fault
  • F3 Discharge sensor (T5) fault
  • F4 Outdoor EEPROM error
  • F5 Outdoor fan speed out of control
  • FL14 Indoor and outdoor units not compatible
  • J0 Outdoor coil overheat in cooling

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Source: DLCMRBH/DLCMHBH Multi-Zone Outdoor Service Manual (sold as Midea, Carrier and Viessmann Vitocal 200-S; Viessmann doc 6225551-03, 12/2024), Table 24 Outdoor Unit Error Display (48 High Heat only) p.27; diagnosis p.51. 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.