Daikin 2MXS40H2V1B Service Manual page 114

Control Specification
4.11.8 Control for Disconnection of the Discharge Pipe Thermistor
Outline The disconnection of the discharge pipe thermistor is detected by comparing the discharge pipe
temperature with the condensing temperature. If the discharge pipe thermistor is disconnected,
the outdoor electronic expansion valve opens according to the outdoor temperature and the
operation frequency, and operates for a specified time, and then stops.
After 3 minutes of waiting, the operation restarts and checks if the discharge pipe thermistor is
disconnected. If the discharge pipe thermistor is disconnected, the system stops after operating
for a specified time.
If the disconnection is detected 4 times in succession, the system is shut down. When the
compressor runs for 60 minutes without any error, the error counter is reset.
Detail Detect Disconnection
When the starting control (about 660 seconds) finishes, and the 9-minute timer for the
compressor operation continuation is not counting time, the following adjustment is made.
1. When the operation mode is cooling
2. When the operation mode is heating
Adjustment when the thermistor is disconnected
When the disconnection is ascertained, the compressor continues operation for 9 minutes and
then stops.
When the compressor stops repeatedly, the system is shut down.
4.11.9 Gas Pipe Isothermal Control During Cooling
When the units are operating in multiple rooms, the gas pipe temperature is detected and the
outdoor electronic expansion valve opening is adjusted so that the temperature of the gas pipe
in each room becomes equal.
The temperatures are monitored every 40 seconds.
4.11.10SC (Subcooling) Control
Outline The liquid pipe temperature and the heat exchanger temperature are detected and the outdoor
electronic expansion valve opening is compensated so that the SC of each room becomes the
target SC.
Detail Start Conditions
After finishing the starting control (about 660 seconds), all the outdoor electronic expansion
valve(s) in the operating room is/are controlled.
Determine Outdoor Electronic Expansion Valve Opening
The outdoor electronic expansion valve opening is adjusted so that the temperature difference
between the maximum heat exchanger temperature of connected room and the liquid pipe
temperature thermistor becomes constant.
103
When the following condition is fulfilled, the discharge pipe thermistor disconnection is
ascertained.
Discharge pipe temperature + 6°C < outdoor heat exchanger temperature
When the following condition is fulfilled, the discharge pipe thermistor disconnection is
ascertained.
Discharge pipe temperature + 6°C < highest indoor heat exchanger temperature
When the gas pipe temperature > the average gas pipe temperature,
→ the opening degree of outdoor electronic expansion valve in the corresponding room increases.
When the gas pipe temperature < the average gas pipe temperature,
→ the opening degree of outdoor electronic expansion valve in the corresponding room decreases.
When the actual SC is > target SC, open the outdoor electronic expansion valve of the room.
When the actual SC is < target SC, close the outdoor electronic expansion valve of the
room.
SiBE121123_A
Function and Control