Outdoor unit of air conditioner

An outdoor unit of an air conditioner, the outdoor unit comprising:

• a compressor;
• a tank through which refrigerant discharged from the compressor and a liquid exchanging heat with the refrigerant flow;
• pipes connected to the tank;
• a pump that supplies the liquid to the tank;
• a deaerator that removes air bubbles contained in the liquid;
• and
• a housing having a horizontal bottom surface placed on an installation surface and a vertical surface extending upward from the bottom surface, the bottom surface including a first inlet hole and a first outlet hole, and the vertical surface including a second inlet hole and a second outlet hole provided above first inlet hole,
• wherein the pipes include:
• a first pipe connected to an inlet of the pump;
• a second pipe connecting an outlet of the pump and an inlet of the tank;
• a third pipe connecting an outlet of the tank and an inlet of the deaerator;
• and
• a fourth pipe connected to an outlet of the deaerator;
• and
• wherein the first pipe and the fourth pipe are configured to be selectively connected to the second inlet hole and the second outlet hole of the vertical surface in a horizontal direction, or to the first inlet hole and the first outlet hole of the bottom surface in a vertical direction.