Mitsubishi FDT125VNPWVH - Page 93

E57
Insucient refrigerant amount
or detection of service valve closure
1. Applicable model
5. Troubleshooting
All models
Diagnosis Countermeasure
NO
YES
NO
YES
Is the
service valve fully
opened?
Are the
connections of indoor
heat exchanger and/or return air
temperature sensor
connectors OK?
NO
YES
NO
YES
Are the
characteristics of indoor heat
exchanger and/or return air
temperature sensor
OK?
Is the low
pressure during operation
normal?
Indoor heat exchanger, return air temperature sensor
Temperature-resistance characteristics
15
10
5
010304020 50
Temperature sensor resistance (kΩ)
Temperature (°C)
5kΩ at 25°C
(Broken wire)
(Short-circuit)
For the characteristics of indoor heat
exchanger,return air temperature sensor,
see the following graph.
Open fully.
Correct indoor heat
exchanger, return air
temperature sensor
connector connections.
Defective indoor heat
exchanger, return air
temperature sensor
➞
Replace.
Charge refrigerant.
Defective indoor unit
control PCB
➞
Replace.
(Defective indoor heat
exchanger, return air
temperature sensor input
circuits)
2. Error detection method
• Judge insufficient refrigerant
amount by detecting the
temperature differnce between
indoor heat exchanger (Thi-R)
and indoor return air (Thi-A).
3 . Condition of error displayed
When the insucient refrigerant
amount is detected 3 times
within 60 minutes.
4. Presumable cause
• Defective indoor heat
exchanger temperature sensor
• Defective indoor return air
temperature sensor
• Defective indoor unit control
PCB
• Insufficient refrigerant
amount
Note: When the compressor speed is faster than 40 rps or 60 rps
※1
after several minutes
※2
from compressor start, the low refrigerant protection control judges, by
satisfying the under condition for 5 minutes, that it is in the state of gas leakage, and stops the compressor.
Cooling: Indoor return air temperature (Thi-A) – Indoor heat exchanger temperature (Thi-R) < 4 deg C
Heating: Indoor heat exchanger temperature (Thi-R) – Indoor return air temperature (Thi-A) < 4 deg C
※1
: In case of heating at low air temperature.
※2
: Cooling is 5 minutes, heating is 9 minutes.
Error code
Remote control:
LED Green Red
Content
Indoor Stays OFF Keeps flashing
'22 • PAC-SM-412
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