37MGRA EH bA (Communication Malfunction Between Indoor Unit and External Fan Module)/ EH 3A(External Fan DC Bus Voltage Is Too Low Protection)/ EH 3b (External Fan DC Bus Voltage is Too High) Fault) Diagnosis and Solution

37MGRA Diagnostic Codes

Diagnostic codes covered

EH BA, EH 3A, EH 3B

  • EH BA – Communication Error Between the Indoor Unit and External Fan Module
  • EH 3A – External Fan DC Bus Voltage Too Low Protection
  • EH 3B – External Fan DC Bus Voltage Too High Fault

Description: Indoor unit does not receive the feedback from external fan module during 150 seconds. or Indoor unit receives abnormal increases or decreases in voltage from external fan module. Recommended parts to prepare: Indoor main PCB Troubleshooting and repair:

Troubleshooting workflow

EH bA (Communication Malfunction Between Indoor Unit and External Fan Module)/ EH 3A(External Fan DC Bus Voltage Is Too Low Protection)/ EH 3b (External Fan DC Bus Voltage is Too High) Fault) Diagnosis and Solution workflow
EHbA (Communication Malfunction Between Indoor Unit and External Fan Module)/ EH3A(External Fan DC Bus Voltage Is Too Low Protection)/ EH3b (External Fan DC Bus Voltage is Too High) Fault) Diagnosis and Solution workflow

Related diagnostic checks

Workflow source: original 37MGRA-02SM service-manual PDF. Error-code names cross-checked against 37MGRA-04SI.

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