Air conditioner for vehicle

A vehicle air-conditioning apparatus comprising:

• a refrigerant circuit including a compressor, an indoor heat exchange unit, and an external heat exchange unit;
• and
• a control device configured to control the refrigerant circuit, wherein
• the refrigerant circuit includes:
• a hot gas bypass that causes at least a part of a refrigerant compressed by the compressor to be decompressed and return to the compressor without passing through the indoor heat exchange unit and the external heat exchange unit;
• and a flow rate adjustment portion that adjusts a flow rate of the refrigerant flowing through the hot gas bypass, and
• the control device
• is capable of executing a hot gas heating mode that causes a part of the refrigerant compressed by the compressor to flow into the indoor heat exchange unit and the remaining refrigerant to flow through the hot gas bypass, and
• in the hot gas heating mode, executes a fixed mode that drives the compressor at a predetermined fixed rotation speed at start of the hot gas heating mode, and then executes an FF/FB mode that controls a rotation speed of the compressor under feedforward control and feedback control and sets a predetermined initial value in an integral term of feedback control at the time of switching from the fixed mode to the FF/FB mode.