Mitsubishi Electric MXZ-SM72TAM-U1 Service Manual page 99

8-8. How to check the components
8-8-1. Thermistor feature chart
■ Low temperature thermistors
• TH2 (HIC pipe)
• TH3 (Outdoor liquid pipe)
• TH6 (Suction pipe)
• TH7 (Ambient)
Thermistor R0 = 15 kΩ ± 3 %
B constant = 3480 ± 1 %
R =15exp{3480(
t
Temperature
32 °F (0°C)
50 °F (10°C) 9.6 kΩ
68 °F (20°C) 6.3 kΩ
77 °F (25°C) 5.2 kΩ
86 °F (30°C) 4.3 kΩ
104 °F (40°C) 3.0 kΩ
■ Medium temperature thermistor
• TH8 (Heat sink)
Thermistor R50 = 17 kΩ ± 2 %
B constant = 4150 ± 3 %
R =17exp{4150(
t
Temperature
32°F (0°C)
77°F (25°C) 50 kΩ
122°F (50°C) 17 kΩ
158°F (70°C) 8 kΩ
194°F (90°C) 4 kΩ
■ High temperature thermistor
• TH4 (Compressor)
Thermistor R120 = 7.465 kΩ ± 2 %
B constant = 4057 ± 2 %
R =7.465exp{4057(
t
Temperature
68 °F (20°C)
86 °F (30°C)
104 °F (40°C)
122 °F (50°C)
140 °F (60°C)
158 °F ( 70°C )
176 °F ( 80°C )
194 °F ( 90°C )
212 °F ( 100°C ) 13.0 kΩ
230 °F ( 110°C ) 9.8 kΩ
OCH800A_99
1 1
– )}
273+t 273
Resistance value
15 kΩ
1 1
– )}
273+t 323
Resistance value
180 kΩ
1 1
– )}
273+t 393
Resistance value
250 kΩ
160 kΩ
104 kΩ
70 kΩ
48 kΩ
34 kΩ
24 kΩ
17.5 kΩ
50
40
30
20
10
0
−4 −14 32 50 68 86 104 122
−20 −10 0 10 20 30 40 50
Temperature
200
150
100
50
0
257 (°F)
77 122 167 212
25 50 75 100 125
Temperature
500
400
300
200
100
0
77 122 167 212
25 50 75 100
Temperature
(°F)
(°C)
(°C)
248 (°F)
120 (°C)