Mitsubishi Electric FDT125VNVF Technical Manual page 437

Indoor display
Error code
E37
Remote controller:
inverter PCB
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:
RUN light
Keeps flashing
Green LED
Outdoor
control PCB
Keeps flashing
Yellow LED
Outdoor
Keeps flashing
5. Troubleshooting
outdoor heat
exchanger temperature
thermistor connector
connected
properly?
Are the
characteristics of
outdoor heat exchanger
temperature
thermistor
(Broken wire)
(Short circuit)
TIMER light
Content
2 times flash
Outdoor heat exchanger
Red LED
1 time flash
temperature themistor anomaly
Diagnosis
Is the
YES
For the characteristics of outdoor heat exchanger
temperature thermistor, see the following graph.
OK?
YES
Temperature-resistance characteristics
15
10
5kΩ at 25°C
5
0 10 20 30 40
Temperature (°C)
436 436
- - - -
Countermeasure
Correct connector.
NO
Defective outdoor heat
NO
exchanger temperature
thermistor ➞ Replace.
Defective outdoor control
PCB ➞ Replace.
(Defective outdoor heat
exchanger temperature
thermistor input circuit)
50
'12 • PAC-T-174