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2.12 Thermistors in RK(X)B, RK(X)N
Functions of Thermistor
Thermistor Functions
Discharge pipe
1. The discharge pipe thermistor is used for controlling discharge pipe temperature.
If the discharge pipe temperature (used in place of the inner temperature of the
compressor) rises abnormally, the operating frequency becomes lower or the
operation halts.
2. The discharge pipe thermistor is used for detecting disconnection of the discharge
pipe thermistor.
Outdoor heat
exchanger
1. The outdoor heat exchanger thermistor is used for controlling the target discharge
pipe temperature. The system sets the target discharge pipe temperature according
to the outdoor and indoor heat exchanger temperature, and controls the Electronic
Expansion Valve (EXV) opening so that the target discharge pipe temperature can
be obtained.
2. In cooling operation, the outdoor heat exchanger thermistor is used for detecting
the disconnection of the discharge pipe thermistor. When the discharge pipe
temperature drops below the outdoor heat exchanger temperature by more than a
certain value, the discharge pipe thermistor is judged as disconnected.
3. In cooling operation, the outdoor heat exchanger thermistor is used for high
pressure protection.
Indoor heat
exchanger
1. The indoor heat exchanger thermistor is used for controlling the target discharge
pipe temperature. The system sets the target discharge pipe temperature according
to the outdoor and indoor heat exchanger temperature, and controls the Electronic
Expansion Valve (EXV) opening so that the target discharge pipe temperature can
be obtained.
2. In cooling operation, the indoor heat exchanger thermistor is used for freeze-up
protection control. If the indoor heat exchanger temperature drops abnormally, the
operating frequency becomes lower or the operation halts.
3. 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 indoor heat exchanger temperature by more than a
certain value, the discharge pipe thermistor is judged as disconnected.
Outdoor air
1. Used for defrost & outdoor fan speed control.
2. Used for overall current protection & preheating operation control.
Heat sink 1. Used for capturing heat sink temperature. (Applicable for Daikin controller)
Suction pipe
1. Used for Electronic Expansion Valve (EXV) & suction pipe (SH) protection control
in heating.
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