Mitsubishi Heavy Industries V Multi FDC71VNX Technical Manual page 215

Error code
Remote control: E28
1. Applicable model
All models
2. Error detection method
Detection of anomalously low
temperature (resistance) of
remote control temperature
sensor (Thc)
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
• Faulty connection of remote
control temperature sensor
• Defective remote control
temperature sensor
• Defective remote control PCB
Note:
After 10 seconds has passed since remote control temperature sensor was switched from valid to invalid, E28 will not be displayed even if the
sensor harness is disconnected. At same time the sensor, which is effective, is switched from remote control temperature sensor to indoor return
air temperature sensor. Even though the remote control temperature sensor is set to be Effective, the return air temperature displayed on remote
control for checking still shows the value detected by indoor return air temperature sensor, not by remote control temperature sensor.
LED Green Red
Keeps flashing Stays OFF
Indoor
Keeps flashing Stays OFF
Outdoor
5. Troubleshooting
Diagnosis
Is the remote
control temperature sensor
connected properly?
YES
Are the
characteristics of
Is the remote
remote control temperature
control temperature sensor
sensor OK?
connected properly?
Is the thermistor wire
OK?
YES
Are the
characteristics of
Resistance-temperature characteristics of remote control temperature sensor (Thc)
remote control temperature
Temperature (°C) Resistance value (kΩ)
sensor OK?
0 65
Is the thermistor wire
1 62
OK?
2 59
4 53
6 48
8 44
10 40
12 36
14 33
16 30
18 27
20 25
22 23
Resistance-temperature characteristics of remote control temperature sensor (Thc)
24 21
Temperature (°C) Resistance value (kΩ)
26 19
0
28 18
1
2
4
6
8
10
12
14
16
18
20
22
24
26
28
214
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Content
Remote control
temperature sensor anomaly
NO
NO
YES
NO
Temperature (°C) Resistance value (kΩ)
30
32
34
36
38
40
42
44 YES
46
48
50
52
54
56
Temperature (°C)
58
65 30
60
62 32
59 34
53 36
48 38
44 40
40 42
36 44
33 46
30 48
27 50
25 52
23 54
21 56
19 58
18 60
-
'19 • PAC-T-327
Countermeasure
Correct.
Defective remote control
NO
temperature sensor ➞
Replace.
Defective remote control
PCB ➞ Replace.
(Defective remote control
temperature sensor input
circuit)
16
15
14
13
12
11
9.9
9.2
8.5
7.8
7.3
6.7
6.3
5.8
Resistance value (kΩ)
5.4
16
5.0
15
14
13
12
11
9.9
9.2
8.5
7.8
7.3
6.7
6.3
5.8
5.4
5.0