R410A All DC Inverter V5 X Series 50Hz      MCAC-VTSM-2015-10 
28                                                                                                                                                                    Specifications & Performances 
14, 16, 18HP 
 
Key components: 
Oil separator: It is used to separate oil from high pressure and high temperature gas refrigerant, which is 
pumped out from compressor. The separation efficiency is up to 99%, it makes the oil return back to each 
compressor very soon. 
Gas-liquid separator: It is used to store the liquid refrigerant and oil; it can protect the compressor from liquid 
hammering. 
EXV (Electronic Expansion Valve): It is used to adjust refrigerant volume. 
Four-way  valve ST1:  Closed in cooling mode and open in heating mode.  The four-way  valve  is used to 
change the refrigerant flow direction in heating mode. When the ST1 is OFF, the heat exchanger functions as a 
condenser. When the ST1 is ON, the heat exchanger functions as an evaporator. 
SV2: It is used to protect the compressor. When any compressor discharge temperature is higher than 100
o
C, 
SV2 will be open and spray a small amount of liquid refrigerant to cooling compressor, and it will be closed 
when the discharge temperature is lower than 90
o
C. 
SV4: Oil return valve. Opens after the inverter compressor has run for 5 minutes and will close 15 minutes later 
(for single outdoor unit system).   
Every 20 minutes, the SV4 of each outdoor unit will open for 3 minutes (for multiple outdoor unit system). 
SV5: It is used for fast defrosting. In defrosting mode, the opening of SV5 can shorten the refrigerant flowing 
circle, so the defrosting process will takes less time. In cooling mode, it is always off.   
SV6: It is used for by-pass. Open when the discharge temperature is over-high in cooling mode, and close 
when the unit is standby or system is in heating mode. 
SV7: It is used to balance system pressure before starting the unit, and it can guarantee system reliability in 
heating mode under low temperature. 
Pressure switch: It is used to protect the system pressure. When the system pressure is too high or too low, 
the pressure switch will open. Once the pressure switch is open, the compressor will stop, and the compressor 
will restart after ten minutes.