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J4 Main board to IPM board communication error

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

What the control is telling you

Same fault as PC40. 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. With power on, check that at least one LED on the IPM board is lit.
  3. Check the signal cable between the IPM and main board. At the plug: black to white about 5 V DC, black to red about 12 V DC.
  4. Reseat the cable and retry.
  5. Still faulty replace the IPM board, then the outdoor main board, then the whole electric control box.

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

  • FL14 Indoor and outdoor units not compatible
  • J0 Outdoor coil overheat in cooling
  • J1 Indoor coil temperature protection in heating
  • J2 Discharge temperature protection
  • J3 PFC module protection
  • J5 High pressure protection
  • J6 Low pressure protection
  • J8 AC voltage protection

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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.49-50. 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.