Hitachi RAM-90QH5, Service Manual, Page: 59 / 83

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8. Temperature Detection Circuit
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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.
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The circuit of the thermistors is shown as Fig. 8-1 for model RAM-90QH5 and their roles and temperature
measuring points are shown as Table 8-1.
Fig. 8-1 Temperature Detection Circuit