Insufficient Refrigerant Amount Or Detection Of Service Valve Closure - Mitsubishi Heavy Industries FDTC50ZHXV Technical Manual

Error code
Remote controller: E57
Note (1) ( ) is for model 40~60.
1. Applicable model
All models
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).
• In case of model 100-250,
it detects at initial startup in
cooling or dehumidifying
mode after power ON.
(In case of model 40~71 it
cannot detect)
3. Condition of Error displayed
When the insufficient
refrigerant amount is detected 3
times within 30 minutes.
( In case of model 100-250 it
makes anomalous stop at initial
detection)
4. Presumable cause
• Defective indoor heat
exchanger temperature
thermistor
• Defective indoor return air
temperature thermistor
• Defective indoor control PCB
• Insufficient refregerant
amount
Note: Insufficient refrigerant amount preventive control makes compressor stopped, if it judges insufficient refrigerant amount by detecting the
temperature difference between indoor heat exchanger (Thi-R) and indoor return air (Thi-A) for 1 minute after compressor ON in cooling or
dehumidifying mode and for 9 minutes after compressor ON in heating mode. [ in cooling mode: (Thi-A)-(Thi-R)>4degC, in heating mode:
(Thi-R)-(Thi-A)<4degC]
LED Green Red
Keeps flashing Stays Off
Indoor
Keeps flashing 1(2) time flash
Outdoor
5. Troubleshooting
Diagnosis
Is the
service valve fully
opened?
YES
Are the
connections of indoor
heat exchanger and/or return air
temperature thermistor
connectors OK?
YES
Are the
characteristics of indoor heat
exchanger and/or return air
temperature thermistor
OK?
YES
Is the low
pressure during operation
normal?
Indoor unit heat exchanger, return air temperature thermistor
Temperature-resistance characteristics
15
10
5
0
319
–
Content
Insufficient refrigerant amount
or detection of service valve closure
NO
NO
NO
NO
YES
5kΩ at 25°C
10 20 30 40 50
Temperature (°C)
Note (1) 22.5rkΩ at -6°C
–
Countermeasure
Open fully.
Correct indoor heat
exchanger, return air
temperature thermistor
connector connections.
Defective indoor heat
exchanger, return air
temperature thermistor 
Replace.
Charge refrigerant.
Replace indoor control
PCB (Defective indoor
heat exchanger, return air
temperature thermistor
input circuits)