An outdoor unit of an air conditioner may include a compressor having a power terminal and a discharge port that protrudes from an upper surface thereof, and a fixing bracket coupled at a point on the upper surface of the compressor that is spaced apart from the power terminal and the discharge port. The fixing bracket may be provided with a hanging hole to which a hoist may be hooked and a sensor holder on which a temperature sensor may be mounted.

To provide a coolant circulation system that supplies, to a motor, a gas phase coolant in which a superheat degree is suppressed to a low value. The coolant circulation system that circulates a coolant to cool a motor in a vehicle, in which a controller estimates, based on detection signals from sensors, a superheat degree of the coolant that flows out from second heat exchangers, the controller controls a flow rate in first expansion valves such that the superheat degree is maintained within a predetermined range from a lower limit threshold, which is larger than zero, and an upper limit threshold, and the controller supplies the coolant from the second heat exchangers to the motor through a channel.