Code: P4🔧 Midea Mini Split

Midea Mini Split Error Code P4: Inverter Compressor Drive Error (Meaning, Causes, Fixes)

Reviewed 2026-10-24 · Based on 5 manufacturer & service sources

What the code means

Midea's error tables list P4 as "Inverter compressor drive error." The service manuals for the Mission, Mission 2 3D, MTIU cassette/duct and older wall-mount series all describe it the same way: an abnormal inverter compressor drive is detected by a special detection circuit, which checks the communication signal, the voltage and the compressor rotation speed signal. In plain terms, the outdoor electronics tried to run the variable-speed compressor and something in that drive chain didn't respond the way it should. On Midea units with indicator lamps instead of a display, P4 shows as the operation lamp and the timer lamp both flashing 5 times. Newer Midea light commercial manuals use the four-character code PC 04 for the same fault (5 flashes there too) and handle it together with PC 00, the IPM protection code that older manuals call P0.

Likely causes

Safe DIY checks

⚠ Before you start

The outdoor unit of an inverter mini split stores a dangerous charge in its large capacitors even after the power is off, and the IPM check requires discharging them first, so leave anything behind the covers to a licensed HVAC technician. Many newer Midea units use R32 refrigerant, which is mildly flammable, so any compressor replacement must be done by a certified technician.

  1. Turn the unit off at the breaker or outdoor disconnect, wait a few minutes, then restart it and note whether P4 comes back right away or only after running for a while. Tell your technician which.
  2. Make sure nothing is blocking the outdoor unit: clear leaves, snow, covers, plants and debris, and keep the clearance around it open, since Midea checks outdoor ventilation as part of this code.
  3. Look, without opening anything, whether the outdoor fan spins when the unit runs. A fan that never turns points the technician toward the fan side of Midea's flowchart.
  4. If the unit was just installed or moved, call the installer first, since the outdoor wiring is part of their work.
  5. Don't keep power-cycling the unit to force it to run. Repeated restarts with a drive fault can stress the compressor and electronics.

🛠 When to call a pro

  • Check the wiring and connectors between the outdoor main board and the compressor terminals; Midea says to correct the connection or replace the wires and connectors if it's wrong.
  • Test the IPM. Midea's older manuals describe a continuity check with the power off and the large capacitors fully discharged: measure between P and U, V, W, N, and between U, V, W and N, where a good module reads open or several megohms. Replace the IPM board or the outdoor main board if it fails.
  • Check the outdoor fan and the unit's ventilation; if the fan is at fault, follow Midea's fan-speed troubleshooting (the F5 or EC 07 code family).
  • Measure the compressor winding resistances against the values in the service manual for that compressor model, and replace the compressor if they're out of range.
  • If all of the above are normal, replace the outdoor main board. Midea notes that on some models the board can't be removed separately, so the whole outdoor electric control box is replaced.

Parts that commonly fix it

Always match the part number to your exact model.

⚙

Outdoor control board

Midea's last step when wiring, IPM, fan and compressor check out; match the outdoor unit's model number.

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⚙

Digital multimeter

For the technician's IPM continuity and compressor winding resistance checks.

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Sources

  1. Midea MTIU-09HWFN1-M / MTIU-12HWFN1-M service manual, 17.4.11 Inverter compressor drive error diagnosis and solution (P4): conditions, causes and flowchart, via EasyManuals
  2. Midea Mission 2 3D Inverter series service manual, 5.12 P4 Inverter compressor drive error diagnosis and solution, via ManualsLib
  3. Midea wall-mount inverter service manual, 8.1 indoor unit error display (P4 = operation and timer lamps flash 5 times), 8.2.10 P4 diagnosis, IPM continuity check and compressor checking, via Clim-Cash Martinique
  4. Midea Mission Inverter (MSMBDU-24HRFN1 / MOCA01-24HFN1) service manual, 1.2.10 Inverter compressor drive error (P4), via mcgrp.ru
  5. Midea Light Commercial Inverter Series service manual (R32), error table and 7.7 PC 00/PC 04 Diagnosis and Solution (outdoor electric control box note)

Last reviewed 2026-10-24. Always confirm against the manual for your exact model number.