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Midea R32 M thermal Arctic Mono fault E4

Domestic hot water tank temperature sensor error

Heat pump

What it means

E4 indicates a domestic hot water tank temperature sensor error. M thermal Mono stops running. Error code is displayed on hydronic system main control board for refrigerant system and user interface.

Likely causes

  1. Temperature sensor not connected properly or has malfunctioned. Damaged hydronic system main PCB.
  2. Sensor T5 fault
  3. Sensor wiring fault
  4. Sensor T5 disconnected, sensor malfunction, wiring break, PCB connection issue
  5. Damaged hydronic system main PCB
  6. Insufficient refrigerant caused by refrigerant leakage
  7. Low pressure side blocked by crushed or bent pipe, blocked EXV, or dirty filter
  8. Poor air side heat exchanger heat exchange in heating or DHW mode
  9. Insufficient water flow rate in cooling mode
  10. Outdoor main PCB fault (last resort)

Where to start

  1. Check sensor T5 connection, measure sensor resistance, verify wiring continuity, test sensor response
  2. Identify sensor type based on fault code
  3. Locate corresponding port on refrigerant system main PCB for that model

The full answer, free

  • 46 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 75), 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 R32 M thermal Arctic Mono. Check the model on the data plate before you order parts.

Other Midea R32 M thermal Arctic Mono fault codes