Service Manual

SiUS041638E Thermistor Functions
Functions and Control 32
The conditions are
Tc ≤ – 1° C
Ta – Tc ≥ 10° C
where Ta is the room temperature and Tc is the indoor heat exchanger temperature.
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In heating operation, the indoor heat exchanger thermistor is used for heating peak-cut control.
If the indoor heat exchanger temperature rises abnormally, the operating frequency becomes
lower or the operation halts.
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In heating operation, the indoor heat exchanger thermistor is used for detecting the
disconnection of the discharge pipe thermistor. When the discharge pipe temperature drops
below the highest indoor heat exchanger temperature by more than a certain value, the
discharge pipe thermistor is judged as disconnected.
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When only one indoor unit is operating, the indoor heat exchanger thermistor is used for
subcooling control. The actual subcool is calculated with the liquid pipe temperature and the
indoor heat exchanger temperature. The system controls the electronic expansion valve
openings to obtain the target subcool.
(5) Room
Temperature
Thermistor
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The room temperature thermistor detects the room air temperature and is used for controlling
the room air temperature.