When the outdoor unit remains frozen after a defrost cycle, an organized inspection is required to identify the root cause.
1. Heat exchanger condition
Check if the ice is uniform, if there are contaminants, or areas with restricted airflow.
2. Sensors
Check the coil and outdoor air temperatures and compare them with an independent measurement.
3. Four-way valve
Confirm that the unit actually changes cycle during defrost.
4. Fan and drainage
Check the correct stopping or operation of the fan and free water drainage.
5. Refrigerant circuit
If the previous steps are correct, check pressures, refrigerant quantity, and the actual thermal capacity of the cycle.
6. Controller logic
Finally, check the defrost parameters and any service settings only in accordance with the manual.
