Mitsubishi Heavy Industries V Multi FDC71VNX Technical Manual page 244

Error code
Indoor control PCB
Remote control:
E57
Outdoor control PCB
Outdoor inverter
1. Applicable model
Models FDC71-250
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).
• It detects at initial startup in
cooling or dehumidifying
mode after power ON.
(In case of model FDC71 it
cannot detect)
3. Condition of error displayed
Anomalous stop at initial
detection
4. Presumable cause
• Defective indoor heat
exchanger temperature sensor
• Defective indoor return air
temperature sensor
• Defective indoor unit control
(or main) PCB
• Insufficient refregerant
amount
Note: I nsufficient 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 return air temperature (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
Keeps flashing
Keeps flashing
Yellow LED
PCB
Keeps flashing
5. Troubleshooting
service valve fully
opened?
connections of indoor
heat exchanger and/or return air
temperature sensor
connectors OK?
characteristics of indoor heat
exchanger and/or return air
temperature sensor
Is the low
pressure during operation
Indoor heat exchanger, return air temperature sensor
Temperature-resistance characteristics
(Broken wire)
15
10
5
(Short-circuit)
Red
Content
Stays OFF
Insufficient refrigerant amount
1-time flash
or detection of service valve closure
(Models FDC71-250 only)
Diagnosis
Is the
NO
YES
Are the
NO
YES
Are the
NO
OK?
YES
NO
normal?
YES
5k at 25°C
0 10 20 30 40 50
Temperature (°C)
243
- -
'19 • PAC-T-327
Countermeasure
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 (or main)
PCB ➞ Replace. (Defective
indoor heat exchanger,
return air temperature
sensor input circuits)