Understanding Heat Pump Error Codes
Modern heat pumps display error codes on the controller when a fault is detected. Understanding these codes helps assess urgency and communicate with your engineer.
High Pressure Faults
Codes indicating high refrigerant pressure (H codes, E4): caused by restricted airflow, dirty coil, or overcharge. System shuts off to protect the compressor. Call an engineer.
Low Pressure Faults
Low pressure codes (E5, P5): indicate refrigerant leak or blockage. Requires F-Gas certified engineer.
Communication Errors
Communication faults between units (E9, C9): usually wiring issues or control board faults. Try power cycling; if persistent, call an engineer.
What to Do
Note the code, switch off and back on, observe whether code reappears, and call an engineer with the code if persistent.
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heat pump error codesASHP fault codesheat pump diagnosticsheat pump fault