Thermistor Error; Current Cut - Mitsubishi Heavy Industries SRK25GZ-L1 Handbook

SRK-GZ
(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 (Comp. dome) thermistor temperature char-
acteristics
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.
40
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 suction
and blow out.
¡ 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 temperature, indoor unit heat ex-
changer temperature, outdoor unit heat
exchanger temperature, external tem-
perature)
30
(Broken wire)
25
20
15
10
5
(Shortcircuit)
–10 0 10 20
Temperature (˚C)
[Open phase on compressor output
terminal, compressor lock]
If check results are normal,
compressor is locked.
30 40 50 60 70