Indoor unit displays H9; unit may not heat properly; often related to indoor coil temperature in heating mode.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Indoor coil sensor misreading, Low refrigerant charge, Blocked indoor airflow, Reversing valve malfunction

Safety: Turn off power before opening the indoor unit.

Steps:

1. Clean filters: Ensure indoor filters are clean and airflow is not restricted.
2. Check indoor coil sensor: Verify the sensor is properly attached to the coil and wiring is intact (see E2).
3. Observe heating performance: If air is only slightly warm or cold, there may be a refrigerant or reversing valve issue.
4. Professional diagnosis: A technician should check refrigerant charge, measure coil temperatures, and test the reversing valve operation.

Hard 4/5

Indoor Coil Temperature Sensor (NTC)

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