HVACopedia

Viessmann · Mini-split

PC42 Compressor start failure

High severity Viessmann Vitocal 200-S DLCM(R/H)B multi-zone outdoorViessmann DLFSHB high wall indoor

What the control is telling you

The compressor failed to start.

Applies to: DLCM(R/H)B multi-zone outdoor units with DLFSHBH high wall indoor units (Midea, Carrier, Viessmann)

Likely causes

  • Loose compressor leads
  • Bad compressor winding
  • Bad inverter / main PCB

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. Restart after 2 minutes. If it clears, the unit is fine.
  3. Check both ends of the compressor leads (U, V, W) for loose or burnt terminals.
  4. Measure the three compressor windings. They must match. Unequal = replace the compressor.
  5. Windings good replace the outdoor main PCB / inverter module.

Models that show this code

12 models in Viessmann Vitocal 200-S DLCM(R/H)B multi-zone outdoor, Viessmann DLFSHB high wall indoor

DLCMHBH24CAKDLCMHBH30DAKDLCMHBH36DAKDLCMHBH48EAKDLCMRBH18BAKDLCMRBH36DAKDLCMRBH48EAKDLFSHBH09XAKDLFSHBH12XAJDLFSHBH12XAKDLFSHBH18XAKDLFSHBH24XAK

Other codes on the same units

  • PC30 High pressure protection
  • PC31 Low pressure protection
  • PC40 Main chip to compressor drive chip communication error
  • PC41 Current input detection protection
  • PC43 Compressor phase loss
  • PC44 Zero speed protection
  • PC45 Compressor drive chip (IR / 341 PWM) failure
  • PC46 Compressor speed out of control

Save it for the next call

Star this code in the HVACopedia app and keep the whole library on your phone for jobs with no signal.

Open the app

Source: DLCMRBH/DLCMHBH Multi-Zone Outdoor Service Manual (sold as Midea, Carrier and Viessmann Vitocal 200-S; Viessmann doc 6225551-03, 12/2024), Table 23 Outdoor Unit Error Display p.26; Carrier MS-DLFSHB-01 High Wall Ductless Service Manual (04/2021), Table 9 p.17, p.39. 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.