Indoor unit stops; C4 error displayed; may be associated with coil temperature sensing

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

Open or shorted indoor coil thermistor, Disconnected thermistor plug, Damaged thermistor wiring, Corroded thermistor connection

Safety first: Turn off power before removing covers or touching sensors.

Steps:

Locate the indoor heat exchanger thermistor clipped to the coil (usually a small bead sensor with two wires).
Ensure the sensor is firmly attached to the coil and the connector is fully seated on the PCB.

Technician actions:

Measure thermistor resistance at room temperature and compare with Daikin specifications.
Replace the thermistor if open, shorted, or out of range.
Inspect and repair any damaged wiring between the thermistor and PCB.

Medium 3/5

Indoor Heat Exchanger Thermistor

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