Mitsubishi Electric FDT125VNVF Technical Manual page 391

Error code
Indoor control PCB
E37
Remote controller:
Outdoor control PCB
Outdoor inverter
1. Applicable model
All models
2. Error detection method
Detection of anomalously low
temperature (resistance) on
the outdoor heat exchanger
temperature thermistor
3. Condition of Error displayed
• When the temperature thermistor
detects -50°C or lower for 20
seconds continuously within 2
minutes to 2 minutes 20 seconds
after the compressor ON, the
compressor stops. After 3-minutes
delay, the compressor starts again
automatically, but if this anomalous
temperature is detected 3 times
within 40 minutes.
• When -50°C or lower is detected for 5
seconds continuously within 20 second
after compressor ON.
4. Presumable cause
• Defective outdoor control
PCB
• Broken thermistor harness or
temperature sensing section
• Disconnected wire connection
(connector)
Note:
LED Green
Keeps flashing
Keeps flashing
Yellow LED or Red LED Green LED
PCB
Keeps flashing
5. Troubleshooting
Is the
outdoor heat
exchanger temperature
thermistor connector
connected
properly?
YES
Are the
characteristics of
outdoor heat exchanger
temperature
thermistor
OK?
Temperature-resistance characteristics
(Broken wire)
15
10
5
(Short circuit)
Red
Content
Stays OFF
Outdoor heat exchanger
1 time flash
temperature themistor anomaly
Keeps flashing
Diagnosis
NO
For the characteristics of outdoor heat exchanger
temperature thermistor, see the following graph.
NO
YES
5kΩ at 25°C
0 10 20 30 40 50
Temperature (°C)
390
- -
'12 • PAC-T-174
Countermeasure
Correct connector.
Defective outdoor heat
exchanger temperature
thermistor ➞ Replace.
Defective outdoor control
PCB ➞ Replace.
(Defective outdoor heat
exchanger temperature
thermistor input circuit)