Daikin D-Series Service Manual page 78

SiBE12-522
D Indoor Heat 1. The indoor heat exchanger thermistors are used for controlling target discharge
Exchanger
Thermistor (DCN)
2. The indoor heat exchanger thermistors are used for preventing freezing.
3. The indoor heat exchanger thermistors are used for anti-icing control.
4. During heating: the indoor heat exchanger thermistors are used for detecting disconnection
5. The indoor heat exchanger thermistors are used for detecting incorrect wiring.
6. The indoor heat exchanger thermistors are used for sub-cooling control.
7. The indoor heat exchanger thermistors are used for heating isothermal control of heat
E Liquid Pipe 1. In heating, the liquid pipe thermistors are used for sub-cooling control.
Thermistor (DLN)
Function and Control
temperature.
The system sets a target discharge pipe temperature according to the outdoor and indoor
heat exchanger temperature, and controls the electronic expansion valve opening so that
the target discharge temperature can be obtained.
During the cooling operation, if the temperature drops abnormally, the operating frequency
becomes lower, then the operation halts.
During the cooling operation, if the heat exchanger temperature in the room where operation
is halted becomes -1°C, or if the room temperature - heat exchanger temperature in the
room where operation is halted becomes ≥10°C, it is assumed as icing.
of the discharge pipe thermistor.
When the discharge pipe temperature becomes lower than the indoor heat exchanger
temperature, the discharge pipe thermistor is judged as disconnected.
During checking incorrect wiring, refrigerant is passed in order from the port A to detect a
heat exchanger temperature, and then wiring and piping will be checked.
The actual sub-cooling is calculated from the liquid pipe temperature and the heat
exchanger temperature. The system controls the electronic expansion valve opening to
reach the target sub-cooling.
exchanger.
When heating: if the difference in temperature of each room is greater than 8°C, the
electronic expansion valve of the room in which the temperature is higher is opened.
The system calculates the actual sub-cooling with the liquid pipe temperature and the
maximum heat exchanger temperature among all rooms, and controls the opening of the
electronic expansion valve to reach the target sub-cooling.
Function of Main Structural Parts
67