Mitsubishi Heavy Industries SRK100VNXWZRF Service Manual page 102

Error code
E28
Remote control:
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 sensor was switched from invalid to valid, E28 will not be displayed even if the temperature
sensor harness is disconnected. At same time the temperature 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.
RUN light TIMER light
Indoor
display
– –
Green LED Red LED
Outdoor unit
control PCB
Keeps flashing Stays OFF
5. Troubleshooting
Diagnosis
Is the remote
control temperature sensor
connected properly?
YES
Are the
characteristics of
remote control temperature
sensor OK?
Is the remote
Is the temperature sensor
control temperature sensor
wire OK?
connected properly?
YES
Are the
Temperature-resistance characteristics of remote control temperature sensor (Thc)
characteristics of
Temperature (°C) Resistance value (kΩ)
remote control temperature
0 65
sensor OK?
1 62
Is the temperature sensor
2 59
wire OK?
4 53
6 48
8 44
10 40
12 36
14 33
16 30
18 27
20 25
22 23
24 21
Temperature-resistance characteristics of remote control temperature sensor (Thc)
26 19
28 18
Temperature (°C) Resistance value (kΩ)
0
1
2
4
6
8
10
12
14
16
18
20
22
24
26
28
101
-
Content
Remote control
temperature sensor anomaly
NO
NO
NO
YES
Temperature (°C) Resistance value (kΩ)
30
NO
32
34
36
38
40
42
44
46
YES
48
50
52
54
56
58
60
Temperature (°C)
65 30
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
-
'22 • PAC-SM-422
Countermeasure
Correct it. ➞ Insert
connector securely.
Defective remote control
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
5.4
5.0
Resistance value (kΩ)
16
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