Panasonic U-8MF2E8 Service Manual page 22

4. Output of PCB
4-2. SAVE Valve [SAVE]
This valve turns ON for 5 seconds before the inverter compressor starts.
After the inverter compressor starts, the valve is ON for ten seconds. Then it turns OFF.
This valve turns ON for 30 seconds after the outdoor unit stops. Then it turns OFF.
This valve turns ON when high pressure sensor detects 3.4MPa to prevent abnormal pressure.
This valve turns OFF when the high pressure goes down below 3.3MPa.
1
This valve might turn ON when the system capacity is excessive although the inverter compressor operates
at Min. frequency.
This valve turns ON in the following status :
(Compressor discharge temperature - High pressure saturation temperature) < 5°C
Under control of Tube Refrigerant Recovery Control
Under control of heat exchanger select mode
4-3. Refrigerant Control Valve [RCV]
The main purpose of this valve is to detect the flow of refrigerant (refrigerant volume) on the indoor unit when the
outdoor unit heat exchanger is functioning as a condenser. When the valve determines that there are signs of a
low refrigerant level, refrigerant is supplied from the receiver tank to the system.
This valve turns ON when the evaporator is refrigerant shortage.
The heat exchanger of indoor unit is evaporator in cooling operation.
The heat exchanger of outdoor unit is evaporator in heating operation.
This valve turns OFF when the excessive refrigerant is in the condenser.
The heat exchanger of indoor unit is condenser in heating operation.
The heat exchanger of outdoor unit is condenser in cooling operation.
This valve turns OFF when the outdoor unit is stopped.
This valve turns ON at stopped outdoor units when the heat exchanger at another outdoor unit is functioning as
a condenser.
RCV
HP
RBV
LP
RCV
HP
RBV
LP
Receiver tank holds refrigerant
ON
High pressure from RCV pushes the liquid refrigerant out of the receiver tank
Evaporator
Two-phase
flow
Refrigerant shortage in evaporator
Evaporator
Two-phase flow
Sufficient refrigerant is supplied to evaporator
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3WAY SYSTEM
Control Functions