Low Pressure Sensor Anomaly - Mitsubishi Heavy Industries FDT Series Technical Manual

Error code
Indoor control PCB
E54
Remote controller:
Outdoor control PCB
Outdoor inverter
1. Applicable model
Models FDC71-140
2. Error detection method
When anomalous voltage
(pressure) is detected
3. Condition of Error displayed
If the pressure sensor detects 0V
or lower and 3.49V or higher for
5 seconds continuously within
2 minutes to 2 minutes 20
seconds after compressor ON,
the compressor stops. When
the compressor is restarted
automatically after 3-minuts
delay, if this anomaly occurs 3
times within 40 minutes
4. Presumable cause
• Defective low pressure sensor
connection
• Defective low pressure sensor
• Defective outdoor control
PCB
• Improper amount of
refrigerant
• Anomalous refrigeration
circuit
Note:
LED Green
Keeps flashing
Keeps flashing
Yellow
PCB
Keeps flashing
5. Troubleshooting
connection of low pressure
sensor connectors (at sensor side
and PCB side) OK?
pressure (actual
measurement) matched with the value
indicated on the remote
Replace the low pressure sensor.
normal condition
Red
Content
Stays OFF

Low pressure sensor anomaly

1 time flash
Diagnosis
Are the
YES
Are the
controller?
NO
Is
restored?
- 417 -
'12 • PAC-T-173
(Models FDC71-140)
Countermeasure
Correct low pressure sensor
NO
connector connection.
Is refrigerant amount
YES
charged properly?
Is there any anomaly on the
refrigeration circuit?
Defective outdoor control
NO
PCB Replace.
(Defective low pressure
sensor input circuit)
OK
YES