E7 Return Air Temperature Thermistor Anomaly - Mitsubishi SCM40ZS-S Technical Manual

Error code
E7
Remote control:
1. Applicable model
All models
2. Error detection method
Anomalously low temperature
or high temperature (resistance)
is detected by indoor return air
temperature thermistor (Thi-A)
3. Condition of error displayed
• When the temperature thermistor
detects -50°C or lower for
5 seconds continuously, the
compressor stops. After 3-minute
delay, the compressor starts again
automatically, but if this error
occurs again within 60 minutes
after the initial detection.
4. Presumable cause
• Defective return air
temperature thermistor
connector
• Defective return air
temperature thermistor
• Faulty indoor control PCB
Note:
LED Green Red
Keeps flashing 1-time flash
Indoor
– Stays OFF
Outdoor
5. Troubleshooting
Diagnosis
Is the
connection of return
air temperature thermistor
connector OK?
YES
Are the
characteristics of return air
temperature thermistor
OK?
Temperature-resistance characteristic
(Broken wire)
15
10
5
(Short circuit)
0
250
-
Content
Return air temperature
thermistor anomaly
NO
NO
YES
°C
5kΩ at 25
10 20 30 40 50
Temperature (°C)
-
'16 • SCM-T-199
Countermeasure
Correct. → Connect
connector.
Defective return air
temperature thermistor →
Replace.
Defective indoor control
PCB → Replace.
(Defective return air
temperature thermistor
input circuit)