Daikin GQI-Eco Series, Service Manual

Page: 43 / 215

ESIE15-13B Function of Main Components and Thermistors
Function and Control 29

Outdoor Unit
(A) Compressor (M1C)
Inverter drive unit varies compressor operating frequency to control capacity and other
factors.
(B) Electronic Expansion Valve (Y1E)
Provides control to maintain optimum operating condition for high efficiency.
(C) Four Way Valve (Y1S)
Changes operation of cooling / heating.
* Coil energized: heating
Coil not energized: cooling
Outdoor Air Thermistor (R1T)
Used for startup condition control and defrost control.
Discharge Pipe Thermistor (R2T)
Used for discharge temperature protection during compression operation.
Suction Pipe Thermistor (R3T)
Used for suction super heat control by electronic expansion valve.
Heat Exchanger Distributor Pipe Thermistor (R4T)
• Used for calculation of outdoor heat exchanger subcooling during cooling operation.
• Used for judgement of the defrost IN and OUT condition.
Intermediate Heat Exchanger Thermistor (R5T)
Used for calculation of high pressure during cooling operation. (Calculate Pc by detected
temperature and R-410A refrigerant characteristics)
Liquid Pipe Thermistor (R6T)
Used for calculation of indoor unit heat exchanger subcooling during heating operation.
Radiation Fin Thermistor (R10T)
• Used for outdoor fan speed control.
• Used for inverter radiation fin temperature control.
• Used for pressure difference control.

Indoor Unit
Indoor Suction Air Thermistor
Indoor Heat Exchanger Thermistor
R1T Suction air thermistor
R2T
R3T
Heat exchanger thermistor
Cooling:
•
Thermostat control
•
PMV control
•
General frequency control
Heating:
•
Thermostat control
•
PMV control
•
General frequency control
Cooling:
•
Compressor frequency control (target Te)
•
Inverter current protection control
•
Freeze-up control
Heating:
•
Compressor frequency control (target Tc)
•
Inverter current protection control
•
Hot start control
•
Peak cut-off