Service Manual
Table Of Contents
- Cover
- Table of contents
- Part 1 List of Functions
- Part 2 Specifications
- Part 3 Printed Circuit Board Connector Wiring Diagram
- Part 4 Refrigerant Circuit
- Part 5 Functions and Control
- Part 6 Test Operation and Field Settings
- Part 7 Remote Controller
- Part 8 Troubleshooting
- 1. Troubleshooting with LED
- 2. Service Diagnosis
- 3. Error Codes and Description
- 4. Troubleshooting for CTXG, CTXS, FTXS, CDXS, FDXS, FVXS Series
- 5. Troubleshooting for FFQ Series
- 6. Troubleshooting for Branch Provider (BP) Unit
- 7. Troubleshooting for Outdoor Unit
- 8. Thermistor Resistance/Temperature Characteristics
- 9. Pressure Sensor
- 10. Method of Replacing Inverter’s Power Transistors Modules
- Part 9 Appendix
SiUS181631EA Basic Control
Functions and Control 53
2. Basic Control
2.1 Normal Operation
Cooling Operation
Heating Operation
★
Heating operation does not start when the outdoor temperature is above 24
°
CDB (75.2
°
FDB).
2.2 Compressor PI Control
The PI control of the compressor capacity is carried out to keep Te constant during cooling
operation and Tc constant during heating operation to ensure stable unit performance.
Cooling operation
Heating operation
Actuator Operation Remarks
Compressor Compressor PI control
Used for high pressure protection control, low
pressure protection control, discharge pipe
temperature protection control, and compressor
operating frequency upper limit control with inverter
protection control.
Outdoor fan Cooling fan control
Four way valve (Y1S) OFF
Main electronic expansion valve (Y1E) 480 pulse
Subcooling electronic expansion valve
(Y3E)
PI control
Hot gas bypass solenoid valve (Y2S) OFF
This valve turns on with low pressure protection
control.
Actuator Operation Remarks
Compressor Compressor PI control
Used for high pressure protection control, low
pressure protection control, discharge pipe
temperature protection control, and compressor
operating frequency upper limit control with inverter
protection control.
Outdoor fan STEP 7 or 8
Four way valve (Y1S) ON
Main electronic expansion valve (Y1E) PI control
Subcooling electronic expansion valve
(Y3E)
PI control
Hot gas bypass solenoid valve (Y2S) OFF
This valve turns on with low pressure protection
control.
Controls compressor capacity to adjust Te to
achieve target value (TeS).
Te: Low pressure equivalent saturation temperature
TeS: Target Te value
(Varies depending on Te setting, operating
frequency, etc.)
Te setting (Set in setting mode 2)
LM (Normal)
: factory setting
H
3°C
(37.4°F)
6°C
(42.8°F)
9°C
(48.2°F)
Controls compressor capacity to adjust Tc to
achieve target value (TcS).
Tc: High pressure equivalent saturation temperature
TcS: Target Tc value
(Varies depending on Tc setting, operating frequency,
etc.)
Tc setting (Set in setting mode 2)
LM (Normal)
: factory setting
H
43°C
(109.4°F)
46°C
(114.8°F)
49°C
(120.2°F)