Panasonic U-72MF2U9 Service Manual page 24

4. Output of PCB
4-6. By-Pass Valve [BPV]
This valve is for pushing the oil in the balance piping into other outdoor unit.
● This valve turns ON when the oil level of compressor is "2" or "1" in its own outdoor unit and the oil level of
compressor is "0" in other outdoor unit.
* This valve turns ON for 10 seconds and turns OFF for 20 seconds. This operation is repeated while oil is
supplied to others.
* For more information on oil level of compressor, see "Oil Control" section.
4-7. Accumulator Valve [ACV]
The purpose of this valve is to recover oil and refrigerant from the accumulator to the compressor.
● This valve turns OFF when the compressor operation just started.
● This valve turns ON when the compressor is warmed up.
● This valve turns ON while the oil recovery among the systems and defrost control are in progress.
1
● This valve turns ON while the MOV4 is operating.
4-8. O Valve [O
2
This valve works when the outdoor unit receives signal of the refrigerant leakage from the indoor unit.
The indoor unit that transmits the signal of the refrigerant leakage gives "P14"alarm.
2
To activate this function, it is necessary to set it to EEPROM on the main outdoor PCB and indoor PCB.
EEPROM setting in main noutdoor unit
CODE: C1
Setting No.
3
0 This function invalid (factory preset mode)
This valve is turned OFF when the system is normal.
1
This valve is turned ON when the outdoor unit receives signal from the indoor unit.
This valve is turned ON when the system is normal.
2
This valve is turned OFF when the outdoor unit receives signal from the indoor unit.
4
EEPROM setting in indoor unit
CODE: 0B
Setting No.
5
0 Function of EXCT plug short-circuit
1 Indoor unit gives "P14"alarm and transmits the refrigerant leakage signal.
4-9. MOV for Heat Exchanger [MOV1, MOV2]
4-9-1. Type of expansion valves
6
MOV1
MOV2
4-9-2. Power Initialization
7
If no indoor units have started (even once) after the power supply to the outdoor unit, the MOV for heat exchanger
holds the pulse at 480 pulses.
8
9
*]
2
For upper side heat exchanger
For lower side heat exchanger
*O valve is the local supply parts.
2
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3WAY VRF SYSTEM
Control Functions