Protective Devices, Thermistors, Sensors - Daikin FTX25JVEA9 Service Manual

Refrigerant System and Function of Functional Parts of Outdoor Unit
1.3 Protective
A HPS
B Low pressure sensor
C Outdoor air thermistor
D Outdoor unit heat exchanger thermistor
E Outdoor unit liquid pipe thermistor
F Discharge pipe thermistor
G Suction pipe thermistor
H Indoor unit room temperature thermistor
I
J BP unit liquid pipe thermistor
K BP unit gas pipe temperature thermistor
106
Devices, Thermistors,
When the high pressure rose abnormally, HPS is actuated to stop the compressor.
Carries out controls such as low pressure protection (compressor protection), and ending
pump down operation, and judgement of gas shortage.
Carries out controls such as fan tap control (H/L switching), determination of initial
frequency, and compressor protection control.
Carries out the target discharge pipe temperature control and the judgement of defrosting
start.
In cooling operation, carries out the outdoor unit SC control (subcooling control) and the
judgement on defrost resetting.
Carries out the compressor internal temperature protection control (operation halts due to
the discharge pipe abnormal high temperature, gas shortage, etc.)
Carries out the judgement of open-phase operation and the system control.
Carries out the pump down operation.
Instructs the capacity supply to BP unit using the room temperature.
Indoor unit heat exchanger thermistor
Carries out various protection functions and controls of capacity (peak cut, freeze protection,
heat exchanger isothermal control in heating operation, target discharge pipe temperature
control, SH control in cooling operation, SC control in heating operation).
In heating operation, carries out the indoor unit SC control.
In cooling operation, carries out the indoor unit SH control and the cooling gas pipe
isothermal control.
Sensors
Si18-201
Main Functions