Mitsubishi Heavy Industries SRK20ZJX-S Service Manual page 113

Error code
Remote controller:
E57
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).
3. Condition of Error displayed
When the insufficient refrigerant
amount is detected 3 times
within 60 minutes.
4. Presumable cause
• Defective indoor heat
exchanger temperature
thermistor
• Defective indoor return air
temperature thermistor
• Defective indoor control PCB
• Insufficient refregerant
amount
Note: When the compressor speed is 50 rps or under at 5 minutes after the start of compressor or the completion of defrosting, the low refrigerant protection control
judges, by detecting the difference between the indoor heat exchanger temperature (Th
gas low, and stops the compressor.
Cooling: Indoor return air temperature (Th
Heating: Indoor heat exchanger temperature (Th
LED Green Red
Indoor Keeps flashing Stays OFF
Outdoor – 2 times flash
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 heat exchanger, return air temperature thermistor
Temperature-resistance characteristics
(Broken wire)
15
10
5
(Shot circuit)
0
-A) – Indoor heat exchanger temperature (Th
I
-R) – Indoor return air temperature (Th
I
112
-
Content
Insufficient refrigerant amount
or detection of service valve closure
NO
NO
NO
NO
YES
5k at 25°C
10 20 30 40 50
Temperature (°C)
-R) and the indoor return air temperature (Th
I
-R) 4 deg
I
-A) 6 deg
I
-
'10 • SCM-SM-094
Countermeasure
Open fully.
Correct indoor heat
exchanger, return air
temperature thermistor
connector connections.
Defective indoor heat
exchanger, return air
temperature thermistor
Replace.
Charge refrigerant.
Defective indoor control
PCB Replace. (Defective
indoor heat exchanger,
return air temperature
thermistor input circuits)
-A), that it is in the state of
I