Every air conditioner is equipped with 2 motors: a compressor and a fan motor.
If the compressor motor is running, but the fan motor is defective, then the air conditioner will be running but no air will blow out of the front or back unit.
Remove the grill and check the fan blade. If it is jammed or very rigid and difficult to rotate, then the fan motor needs to be replaced.
If the fan blade is rotating, then the fan motor needs to be fixed.
To do so, it is better to call a qualified technician to identify the problem which could be with the selector switch, the capacitor or the motor.