System for fluid pump down using valves

A cooling system comprising:

• an air handling unit configured to distribute air, the air handling unit comprising an evaporator;
• a condensing unit comprising a compressor and a condenser, the compressor fluidly connected to the condenser by a compressor discharge line configured to channel refrigerant from the compressor to the condenser;
• a suction line configured to channel refrigerant from the evaporator to the compressor;
• a liquid line configured to channel refrigerant from the condenser to the evaporator;
• and
• a valve system comprising:
• a motor having a shaft;
• a liquid-line valve connected to the shaft and in fluid communication with the liquid line, the liquid-line valve including a liquid-line channel therethrough, the liquid-line valve rotatable to an open position, in which refrigerant flows through the liquid-line channel, and to a closed position, in which refrigerant is prevented from flowing through the liquid-line channel;
• a suction-line valve connected to the shaft and in fluid communication with the suction line, suction-line valve including a suction-line channel therethrough, the suction-line valve rotatable to an open position, in which refrigerant flows, using suction, through the suction-line channel, and to a close position, in which refrigerant is prevented from flowing through the suction-line channel;
• and
• a controller connected to the motor, the controller configured to, using the motor and the shaft, sequentially actuate the liquid-line valve and the suction-line valve to create at least (i) a first position, in which the liquid-line valve is in the closed position and the suction-line valve is in the closed position, (ii) a second position, in which the liquid-line valve is in the open position, (iii) a third position, in which the liquid-line valve is in the open position and the suction-line valve is in the open position, and (iv) fourth position, in which the liquid-line valve is in a closed position and the suction-line valve is in the open position.