Function Setting; Operation Characteristics In Relation To The Refrigerant Charge - Mitsubishi Electric City Multi PURY-P72TNU-A-BS Manuel D'installation

11-2. Function setting

Make function settings by setting the dipswitches SW4, SW6, and SWP3 on the main board.
Write down the switch settings on the electrical wiring diagram label on the control box front panel for future reference when the control box needs
to be replaced.
・Take the following steps to make temperature unit (ºC or ºF) settings.
① Set the 10th bit of SW6 to ON.
② Set SW4 as shown in the table below to select the setting item No.921. (The setting item No. will be displayed on LED1.)
③ Press SWP3 for two seconds or longer to change the settings. (The settings can be checked on LED3.)
Setting item No.
Temperature unit
921
setting
*1 Make the SW4 setting after the unit is energized.
*2 This will blink while the system is starting up.
・Make various function settings by setting SW5 and SW6, referring to the table below.
Setting content
SW5-1 Centralized control switch
SW5-2 Deletion of connection information
SW5-3
SW5-4
SW5-5
SW5-6
SW5-7
SW5-8
Setting content
SW6-1
SW6-2
SW6-3
SW6-4
High static pressure setting
SW6-5
SW6-6
SW6-7 Low-noise mode selection
SW6-8 Selection of Low-noise or Demand
SW6-9
Selection of Diagnostic display or Function detail
SW6-10
* Do not change the factory settings of SW5-3 through SW5-8.
* Unless otherwise specified, leave the switch to OFF where indicated by "–," which may be set to OFF for a reason.
*1
SW6-5: ON
SW6-4: ON 80 Pa
SW6-4: OFF 30 Pa
*2
SW6-9: ON LED (round type) No. 0 to 1023
SW6-9: OFF Function setting No. 0 to 1023

11-3. Operation characteristics in relation to the refrigerant charge

It is important to have a clear understanding of the characteristics of refrigerant and the operation characteristics of air conditioners before
attempting to adjust the refrigerant charge in a given system.
・During cooling operation, the amount of refrigerant in the accumulator is the smallest when all indoor units are in operation.
・During heating operation, the amount of refrigerant in the accumulator is the largest when all indoor units are in operation.
・Refrigerant undercharge creates a tendency for the discharge temperature to rise.
・Changing the amount of refrigerant in the system while there is refrigerant in the accumulator has little effect on the discharge temperature.
・The higher the high pressure level, the more likely it is for the discharge temperature to rise.
・The lower the low pressure level, the more likely it is for the discharge temperature to rise.
・When the amount of refrigerant in the system is adequate, the compressor shell temperature is 10 to 60ºC (50 to 140ºF) higher than the low-
pressure saturation temperature. If the temperature difference between the compressor shell temperature and low-pressure saturation
temperature is 5ºC (41ºF) or less, refrigerant overcharge is suspected.
WT09106X03
SW4 0: OFF, 1: ON *
1 2 3 4 5
1 0 0 1 1
Without connection to the
centralized controller
–
–
–
–
–
–
–
–
–
–
Performance priority
setting
SW6-5: OFF
60 Pa
0 Pa
SW6-10: ON
1
6 7 8 9 10
0 0 1 1 1
Setting
OFF
With connection to the centralized
Normal control
Preset before shipment
Setting
OFF
–
–
–
Refer to *1.
–
Low-noise priority
Low-noise (Night)
Refer to *2.
SW6-10: OFF
LED (7seg) No. 1024 to 2047
LED (7seg) No. 0 to 1023
GB-46
Setting (LED3 display) *
Unlit
ºC
Switch setting timing
ON
Before being energized
controller
Deletion Before being energized
Switch setting timing
ON
–
–
–
Refer to *1. Before being energized
–
Any time after being energized
Demand Before being energized
Refer to *2. Any time after being energized
2
Lit
ºF
–
–
–
–
–
–
–
–
–
–