Panasonic U-72MF2U9 Service Manual

Also see for U-120MF2U9: Installation instructions Operating instructions Installation instructions Technical data

Contents

3WAY VRF SYSTEMControl Functions1 - 141234567894. Output of PCB4-2. Save Valve [SAVE]● This valve turns ON for 5 seconds before the inverter compressor starts.After the inverter compressor starts, the valve turns ON for 10 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 496psi (3.42MPa) to prevent abnormal pressure.This valve turns OFF when the high pressure goes down below 481.5psi (3.32MPa).● This valve might turn ON when the system capacity is excessive although the inverter compressor operates atMin. frequency.● This valve turns ON in the following status :(Compressor discharge temperature - High pressure saturation temperature) < 9deg F (5deg C)● Under control of Tube Refrigerant Recovery Control● Under control of heat exchanger select mode● This valve turns ON when low pressure sensor goes down 24.7psi (0.17MPa) to prevent abnormal pressure.This valve turns OFF when low pressure sensor increase 29psi (0.20MPa) or over.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 theoutdoor unit heat exchanger is functioning as a condenser. When the valve determines that there are signs of a lowrefrigerant 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 acondenser.EvaporatorRBVRCVLPHPRefrigerant shortage in evaporatorReceiver tank holds refrigerantTwo-phaseflowEvaporatorRBVRCVLPHPSufficient refrigerant is supplied to evaporatorHigh pressure from RCV pushes the liquid refrigerant out of the receiver tankONTwo-phase flow