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77

During heating operation, the temperature detected by the indoor pipe temperature sensor is above 60

“C.

• Air short circuit at indoor unit
• Clogged indoor unit air filter
• Dust accumulation on the indoor unit heat exchanger
• 2/3 way valve closed
• Faulty indoor unit fan motor
• Excessive refrigerant
• Clogged expansion valve or strainer
• Faulty indoor pipe temperature sensor
• Faulty indoor unit PCB

78

Freeze prevention control takes place (when indoor pipe temperature is lower than 2

“C)

• Air short circuit at indoor unit
• Clogged indoor unit air filter
• Dust accumulation on the indoor unit heat exchanger
• 2/3 way valve closed
• Faulty indoor unit fan motor
• Refrigerant shortage (refrigerant leakage)
• Clogged expansion valve or strainer
• Faulty indoor pipe temperature sensor
• Faulty indoor unit PCB

79

• When heating operation, when indoor pipe temperature is below 10

“C

• When cooling operation, when indoor pipe temperature is above 45

“C

• Connector in poor contact
• Faulty sensor
• Faulty outdoor unit PCB
• 4-way valve defective

80

• When the different between indoor intake air temperature and indoor pipe temperature is above 10

“C or indoor pipe temperature

is below -1.0

“C

Remark:
When the indoor standby unit is freezing, the outdoor unit transfers F17 error code to the corresponding indoor unit and H39 to
other indoor unit(s).

• Wrong wiring connection
• Faulty sensor
• Faulty expansion valve