TROUBLESHOOTING
108
PD
Description
• High temperature protection of air side heat exchanger refrigerant outlet in cooling mode. When the
air side heat exchanger refrigerant outlet temperature is higher than 61°C for more than 3 seconds, the
system displays Pd protection and the unit shuts down. When the air side heat exchanger refrigerant outlet
temperature returns below 55°C, Pd is removed and normal operation resumes.
• The unit shuts down.
• The error code is displayed on the main PCB and user interface.
Possible causes
• Temperature sensor not connected properly or has malfunctioned.
• Poor condenser heat exchange.
• Fan motor damaged.
• Main PCB is damaged.
PD
↓
Air side exchanger refrigerant outlet temperature
sensor is loose1
YES
→
Ensure the temperature sensor is connected
properly
NO
↓
Air side exchanger refrigerant outlet temperature
sensor
has short-circuited or failed2
YES
→
Replace the temperature sensor
NO
↓
The air side device heat exchange is poor3
YES →
Inspect the system and fix the error
NO
↓
The fan or fan motor is blocked or damaged
YES →
Inspect the system and fix the error
NO
↓
Replace main PCB
Notes:
1 Air side exchanger refrigerant outlet temperature sensor and outdoor ambient temperature sensor
connection is port CN9 on the unit’s main PCB.
2 Measure sensor resistance. If the resistance is too low, the sensor has short-circuited. If the resistance is not
consistent with the sensor’s resistance characteristics table, the sensor has failed.
3 Check air side heat exchanger, fan and air outlets for dirt/blockages.
4 The high pressure switch connection is port CN13 on single-phase units and port CN31 on three-phase units.
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