A5

Daikin Indoor Heat Exchanger Frost / Overheat Protection

Indoor unit stops frequently; A5 displayed; may occur in heating or cooling

Safety Warning

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

Blocked indoor air filter, Dirty indoor heat exchanger coil, Faulty indoor thermistor (heat exchanger sensor), Low refrigerant causing coil freeze

How to Fix / Troubleshooting

Safety first: Turn off the unit before cleaning filters or coils.

User steps:

Open the front panel and remove the air filters. Wash them with mild detergent and water, dry completely, and reinstall.
Inspect the indoor coil behind the filters; if heavily dust-laden, gently vacuum with a soft brush or have it professionally cleaned.
Ensure all supply and return air paths are unobstructed (no furniture blocking airflow).

Technician steps:

Check the indoor heat exchanger thermistor resistance vs. temperature; replace if out of specification.
Verify refrigerant charge and look for signs of coil icing or low suction pressure.
Correct any airflow issues (fan speed, blower wheel cleaning).

Repair Difficulty

Medium 3/5

Required Part

Indoor Heat Exchanger Thermistor

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