Outdoor Air Temperature Thermistor Anomaly - Mitsubishi Heavy Industries FDT Series Technical Manual

Error code
Indoor control PCB
E38
Remote controller:
Outdoor control PCB
Outdoor inverter
Note (1) Value in is for the models SRC40-60.
1. Applicable model
All models
2. Error detection method
Detection of anomalously
low temperature (resistance)
on outdoor air temperature
thermistor
3. Condition of Error displayed
• When the temperature thermistor
detects -45(-55)°C or lower for
5 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 -45(-55)°C or lower is detected
for 5 seconds continuously within 20
second after compressor ON.
Note (1) Value in ( ) are for the models
SRC 40-60.
4. Presumable cause
• Defective outdoor control
PCB
• Broken thermistor harness or
temperature sensing section
(Check molding.)
• Disconnected wire connection
(connector)
Note:
LED Green
Keeps flashing
Keeps flashing
Yellow
PCB
Keeps flashing
5. Troubleshooting
Is
the outdoor air
temperature thermistor connector
connected properly?
YES
Is the
characteristics of the
outdoor air temperature
thermistor
OK?
• Models SRC40-60
Temperature-resistance characteristics
(Broken wire)
15
10
5
(Short circuit)
0 10
Temperature (°C)
• Models FDC71 - 140
Temperature-resistance characteristics
(Broken wire)
35
30
25
20
15
10
5
0
(Short circuit)
0 10
Temperature (°C)
Red
Content
Stays OFF
Outdoor air temperature
1 8 time flash
thermistor anomaly
Diagnosis
NO
For the characteristics of outdoor air
temperature thermistor, see the following graph.
NO
YES
5k at 25°C
20 30 40 50
20 30 40 50
- 401 -
'12 • PAC-T-173
Countermeasure
Correct connector.
Defective outdoor air
temperature thermistor
Replace.
Defective outdoor control
PCB Replace.
(Defective outdoor air
temperature thermistor
input circuit)