Control Specification; Thermistor Functions - Daikin CTXG09QVJUW Service Manual

Control Specification

4. Control Specification

4.1

Thermistor Functions

(2) Outdoor Heat
Exchanger
Thermistor
(1) Discharge Pipe
(1) Discharge
Pipe Thermistor
(2) Outdoor Heat
Exchanger
Thermistor
(3) Outdoor
Temperature
Thermistor
(4) Gas Pipe
Thermistor
80
(3) Outdoor
Temperature
Thermistor
Four way valve
Thermistor
Compressor
The illustration is for the 4-room models as representative and have 4 lines of indoor unit system (A
The 3-room models have 3 lines (A
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.
The discharge pipe thermistor is used for detecting disconnection of the discharge pipe
thermistor.
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 opening so
that the target discharge pipe temperature can be obtained.
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.
In cooling operation, the outdoor heat exchanger thermistor is used for high pressure protection.
The outdoor temperature thermistor detects the outdoor air temperature and is used for
refrigerant shortage detection, input current control, outdoor fan control, liquid compression
protection function, and so on.
In cooling operation, the gas pipe thermistor is used for gas pipe isothermal control. The system
controls electronic expansion valve opening so that the gas pipe temperature in each room
becomes equal.
Expansion valve
EVA
EVB
EVC
EVD
(7) Room
Temperature
Thermistor
(4) Gas Pipe
Thermistor
–
C) and 2-room models have 2 lines (A
SiUS121630EA
(5) Liquid Pipe
Thermistor
D C B A
(6) Indoor Heat
Exchanger
Thermistor
(R23838)
–
–
B).
Functions and Control
D).