Panasonic Aquarea T-CAP R32 fault F20

What it means

During operation of cooling and heating, when temperature above 117°C is detected by the outdoor discharge pipe temperature sensor.

Likely causes

1. Compressor tank temperature exceeding 107°C
2. Excessive compressor load or insufficient cooling of compressor
3. Refrigerant circuit fault causing high discharge/tank temperature
4. Faulty outdoor discharge pipe temperature sensor
5. 2/3 way valve closed
6. Refrigerant shortage (refrigerant leakage)
7. Clogged expansion valve or strainer
8. Faulty outdoor unit PCB (main)
9. Faulty compressor
10. Inefficient compressor (worn or faulty compression)
11. Insufficient refrigerant
12. Water leakage or insufficient water flow rate in the system
13. Excessive amount of refrigerant
14. Excess insertion of refrigerant
15. Heat releasing obstruction
16. Dirty condenser, attachment of impurity
17. Compressor malfunction
18. Clogged capillary, expansion valve malfunction
19. Clog by moisture
20. Lack of refrigerant gas
21. Mixture of air (insufficient evacuation)
22. Mixture of moisture
23. Mixing of unregulated/incompatible compressor oil between R410A and R32 systems
24. Energy or electric current limitation requiring high power device shutdown
25. Removing refrigerant pipes while compressor is running and valve is open

Where to start

1. Measure compressor tank temperature and compare against control bands to determine expected compressor behaviour
2. Check compressor frequency reduction behaviour against temperature thresholds (90°C, 96°C/97°C, 113°C/115°C, 117°C)
3. Count number of overheat stop occurrences within 30 minutes