Error 73 (7 Green, 3 Red Flashes) — Heat-exchange thermistor (outlet / intermediate) error

What does 73 mean?

The hydraulic unit's green LED flashes seven times and the red LED flashes three times. This indicates an error with a heat-exchange thermistor, specifically at the outlet or an intermediate point in the system.

• Faulty heat-exchange thermistor.
• Loose or damaged wiring connected to the thermistor.
• Improper heat exchange due to low refrigerant or airflow issues.

Click steps to track your progress.

1. 1

   Restart the heat pump system by turning off the main power for at least one minute, then switching it back on.

2. 2

   Check that the outdoor unit is free from obstructions and has good airflow.

3. 3

   Ensure that the indoor unit's filters are clean and not restricting airflow.

4. 4

   If the error continues, contact a qualified technician to diagnose the specific thermistor and system components.