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Midea Heat pump fault HD

Communication fault between master unit and slave unit

Heat pump

What it means

Communication fault between master unit and slave unit. Triggered when, for a cascade system, the communication failure between master unit and slave unit lasts 2 minutes and above.

Likely causes

  1. Communication cables between port H1H2E1 disconnected or misconnected
  2. Dip switch S3-1/2/3 incorrectly set or duplicated address across units
  3. Time difference of providing power supply for master unit and slave unit is greater than 1 min
  4. Faulty Main Control PCB

Where to start

  1. Check communication cables between port H1H2E1 for disconnection or miswiring
  2. Confirm Dip switch S3-1/2/3 of each unit are all correct and not repeated
  3. Check time difference of providing power supply between master unit and slave unit

The full answer, free

  • The readings and component tests from the manual
  • How to put it right, step by step
  • The manual page for this fault (page 106), 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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