PC46 Compressor speed out of control

What the control is telling you

Compressor speed does not follow the command.

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

Likely causes

• High load / restriction
• Poor outdoor airflow
• Bad compressor or 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. Measure the input current on the supply wire. Limits: 15 A on 18K; 18.5 A on 27K and 18K high heat; 22.5 A on 36K and 27K high heat; 28 A on 48K and 36K high heat.
3. Outdoor air above 122 F (50 C) = outside the range, shut it down.
4. Check outdoor airflow and clean the coil.
5. Check for a refrigerant restriction. If blocked: recover the charge, blow the lines through with nitrogen, evacuate and recharge.
6. If none of the above, replace the outdoor main board (or the electric control box) and retest.

Models that show this code

12 models in Midea DLCM(R/H)B multi-zone outdoor, Midea DLFSHBH wall indoor (DLCM multi-zone)

Other codes on the same units

• PC42 Compressor start failure
• PC43 Compressor phase loss
• PC44 Zero speed protection
• PC45 Compressor drive chip (IR / 341 PWM) failure
• PC49 Compressor over-current
• PCA1 Refrigerant pipe condensation protection
• PH09 Anti-cold-air in heating
• PH90 Evaporator coil too hot