Suction Pipe Temperature Thermistor Anomaly - Mitsubishi Heavy Industries FDT Series Technical Manual

Error code
Indoor control PCB
E53
Remote controller:
Outdoor control PCB
Outdoor inverter
1. Applicable model
Models FDC71-140
2. Error detection method
When the suction pipe
temperature thermistor detects
anomalously low temperature
3. Condition of Error displayed
If the temperature thermistor
detects -50°C or lower for 5
seconds continuously within
10 minutes to 10 minutes 20
seconds after compressor ON,
the compressor stops. When
the compressor is restarted
automatically after 3-minutes
delay, if this anomaly ocuurs 3
times within 40 minute.
4. Presumable cause
• Defective suction pipe
temperature thermistor
connection
• Defective suction pipe
temperature thermistor
• Defective outdoor control
PCB
Note:
LED Green
Keeps flashing
Keeps flashing
Yellow
PCB
Keeps flashing
5. Troubleshooting
Is the connection
of suction pipe temperature thermistor
connector OK?
characteristics of suction pipe
temperature thermistor OK?
Temperature-resistance characteristics
(Broken wire)
15
10
5
(Short circuit)
Red
Content
Stays OFF
temperature thermistor anomaly
1 time flash
Diagnosis
YES
Are the
YES
5k at 25°C
0 10 20 30 40 50
Temperature (°C)
- 416 -
'12 • PAC-T-173
Suction pipe
(Models FDC71-140)
Countermeasure
Correct connection of
NO
suction pipe temperature
thermistor connector.
Defective suction pipe
NO
temperature thermistor
Replace.
Defective outdoor control
PCB Replace.
(Defective suction pipe
temperature thermistor
input circuit)