Hitachi RAM-71QH5, Service Manual

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10. Temperature Detection Circuit
●
The outdoor units (this model) provides with the outdoor temperature thermistor, DEF (defrost) thermistor,
OH (overheat) thermistor and electric expansion valve thermistor so that they detect the temperatures of the
unit and control the system.
●
The circuit of the thermistors is shown as Fig. 10-1 for model RAM-71QH5 and their roles and temperature
measuring points are shown as Table 10-1.
Fig. 10-1 Temperature Detection Circuit
R110: 1.28K‰ – 5%
B100/110:
4400K – 150K
R0: 5.8K‰ – 5%
B0/25: 3400 – 2%
R35: 1.433K‰ – 2%
B0/70: 3400K – 2%
R25: 2.0 K‰ – 5%
B25/50: 3500K – 2%
CN9
R316
R312
R313
R307 R308 R309 R310
R31
1
R315
C31
1
C310
C309
C308 C307 C306 C305 C304
0V
0V 0V
JW11
JW12
JW13
JW14
R321
R322
R323
R324
JW7
JW8
JW9
JW10
R317
R318
R319
R320
+ 5V
R314
CN8
CN7
CN6
CN5
+ 5V
0V
R301
R302 R303
C312
+ 5V
IC7
X 2
X 1
X 0
X 5
X 6
X 7
X 4
X
C
B
A
X 3
R332 R333 R334
0V