Return Air Temperature Sensor Anomaly - Mitsubishi Heavy Industries FDUA160AVSAVH Service 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 sensor (Thi-A)
3. Condition of error displayed
• When the temperature sensor
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 sensor connector
• Defective return air
temperature sensor
• Faulty indoor unit control
PCB
Note:
LED Green Red
Keeps flashing 1-time flash
Indoor
Keeps flashing Stays OFF
Outdoor
5. Troubleshooting
Diagnosis
Is the
connection of return
air temperature sensor
connector OK?
YES
Are the
characteristics of return air
temperature sensor
OK?
Temperature-resistance characteristic
(Broken wire)
15
10
5
(Short-circuit)
0
78
-
Content
Return air temperature
sensor anomaly
NO
NO
YES
°C
5kΩ at 25
10 20 30 40 50
Temperature (°C)
-
'21 • PAC-SM-398
Countermeasure
Correct it. ➞ Connect
connector.
Defective return air
temperature sensor ➞
Replace.
Defective indoor unit
control PCB ➞ Replace.
(Defective return air
temperature sensor input
circuit)