Mitsubishi SCM80ZA Manual page 59

(3) Inspection procedures corresponding to detail of trouble
Thermistor error
Is connector connection good?
YES
Is thermistor resistance value good?
YES
Replace PCB.
Discharge pipe thermistor temperature characteristics
Temperature (˚C) Resistance (kΩ)
0 164
5 127
10 99
15 78
20 62
25 50
30 40
35 32
40 26
45 21
50 17
55 14
60 12
65 10
Current cut
Does current cut operate when
operating inverter with compressor
wire disconnected?
YES
Is output voltage applied to all 3
phases of power transistor?
YES
Is there any shortcircuit?
YES
Inspect compressor.
NO
Correct connection.
NO
Replace thermistor.
Temperature (˚C) Resistance (kΩ)
70 8.7
75 7.3
80 6.2
85 5.3
90 4.5
95 3.9
100 3.3
105 2.9
110 2.5
115 2.2
120 1.9
125 1.6
130 1.4
135 1.3
NO
Defective inverter
NO
Defective inverter
NO
Secure space for inlet
and outlet.
● Check compressor wiring visually.
● Check insulation resistance. (1 MΩ or over)
● Check coil wire resistance. (Few Ω)
[Broken thermistor wire,
connector poor connection]
Thermistor temperature characteristics
(Room temp., indoor and outdoor unit
heat exchanger temp., outdoor temp.)
30
25
(Broken wire)
20
15
Resistance (kΩ)
10
5
–10 0 10
(Shortcircuit)
Temperature (˚C)
[Open phase on compressor output
terminal, compressor lock]
If check results are normal,
compressor is locked.
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