Mitsubishi Heavy Industries SRK20HC-S Technical Manual page 30

(2) Self diagnosis display on indoor unit
RUN lamp
1 time flash
TIMER lamp
2 time flash
ON
6 time flash
TIMER lamp
1 time flash
RUN lamp
2 time flash
keeps flashing
4 time flash
1 time flash
2 time flash
RUN lamp
ON
5 time flash
6 time flash
(3) Inspection procedures corresponding to detail of trouble
Thermistor error
Is connector connection good?
YES
Is thermistor resistance value good?
YES
Replace PCB.
N Discharge pipe thermistor temperature characteristics
Temperature (˚C) Resistance (kΩ)
0
5
10
15
20
25
30
35
40
45
50
55
60
65
Outdoor unit LED
OFF
OFF
OFF
OFF
OFF
OFF
1 time flash
2 time flash
5 time flash
6 time flash
NO
Correct connection.
NO
Replace thermistor.
Temperature (˚C) Resistance (kΩ)
164 70
127 75
99 80
78 85
62 90
50 95
40 100
32 105
26 110
21 115
17 120
14 125
12 130
10 135
Trouble
Heat exchanger thermistor error
Room temperature thermistor error
Indoor fan motor error
Outdoor temperature thermistor
error
Outdoor unit heat exchanger
thermistor error
Discharge pipe thermistor error
Current cut
Outdoor unit error
Compressor overheat
Serial signal transmission error
N Thermistor temperature characteristics
(Room temp., indoor unit heat exchanger
temp., outdoor unit heat exchanger
temp., outdoor temp.)
8.7
7.3
6.2
5.3
(Broken wire)
4.5
3.9
3.3
2.9
2.5
2.2
1.9
(Shortcircuit)
1.6
1.4
1.3
28
- -
Cause
¡ Broken heat exchanger thermistor wire, connector
poor connection
¡ Broken room temperature thermistor wire,
connector poor connection
¡ Defective fan motor, connector poor connection
¡ Broken outdoor thermistor wire, connector poor
connection
¡ Broken heat exchanger thermistor wire, connector
poor connection
¡ Broken discharge pipe thermistor wire, connector
poor contact
¡ Compressor lock.
¡ Closed service valve.
¡ Compressor faulty
¡ Overload operation (51C operation)
¡ Gas shortage.
¡ Defective discharge pipe thermistor.
¡ Broken signal wire.
¡ Defective indoor/outdoor unit PCB.
[Broken thermistor wire,
connector poor connection]
30
25
20
15
10
5
–10 10 20
0 30 40
Temperature (˚C)
70
50 60