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Midea Heat pump fault H4

Repeated L1* protection (3 times in 60 mins)

Heat pump

What it means

H4 is triggered when 'L1*' fault occurs 3 times within 60 minutes, indicating a recurring inverter module protection event.

Likely causes

  1. Recurring L1* fault (L1E, L11, or L12 type overcurrent protections)
  2. Faulty inverter power module
  3. Faulty three-phase bridge rectifier (3Ph models)

Where to start

  1. Check the specific L** code history on digital display panel on the Main Control PCB
  2. Refer to Part 4 Appendix: Guide for identifying inverter PCB failure to determine PCB status before component replacement
  3. Set multimeter to diode test function (secondary tube available)

The full answer, free

  • 6 more checks in order
  • The readings and component tests from the manual
  • How to put it right, step by step
  • The manual page for this fault (page 147), right under the answer
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Safety: Isolate the outdoor unit and any backup heater, and give the inverter capacitors time to discharge before you open the electrics. Anything on the refrigerant circuit needs F-gas certification.

From the Midea manual for the Heat pump. Check the model on the data plate before you order parts.

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