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Midea M-Thermal Arctic HT R290 Mono fault E3

T1 electric heater/AHS water outlet temperature sensor error

Heat pump

What it means

T1 Electric Heater/AHS water outlet temperature sensor error. Main Control PCB cannot detect the right T1 sensor value. Triggered when IBH function is on (Dip switch S1-3/4 set IBH available, and User Interface- For Serviceman - Other heat source - IBH function=1) or when AHS function is on (User Interface- For Serviceman - Other heat source - AHS function=1).

Likely causes

  1. Temperature sensor connection on Main Control PCB is loose, misconnected, broken or moisturized
  2. Main Control PCB fault
  3. Sensor wiring/connection fault at CN39
  4. Main Control PCB failure

Where to start

  1. If Yes, check if temperature sensor connection on Main Control PCB is loose, misconnected, broken or moisturized; if Yes, reconnect the temperature sensor correctly and keep it dry
  2. If No to all above, replace Main Control PCB
  3. Check Dip switch S1-3/4 IBH setting

The full answer, free

  • 3 more checks in order
  • How to put it right, step by step
  • The manual page for this fault (page 111), 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 M-Thermal Arctic HT R290 Mono. Check the model on the data plate before you order parts.

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