Abstract: A method monitors an air-conditioner having a semi-conductor gas sensor, the method including: determining that a refrigerant leakage has occurred on condition that the detection value is equal to or greater than a first threshold when the fan is in operation; starting operation of the fan as a provisional operation if the detection value is equal to or greater than a second threshold when the fan is not in operation; stopping the provisional operation of the fan; determining that a refrigerant leakage has occurred on condition that the detection value is equal to or greater than a third threshold after stopping the provisional operation of the fan; and taking a predetermined action for outputting alarm information and/or limiting supply of refrigerant to the heat exchanger when a refrigerant leakage is determined to have occurred.

Abstract: A hydraulic booster is provided between a M/C pressure and a W/C pressure. The hydraulic booster is composed of a pump and an amplifying piston amplifying the brake fluid amount discharged from the pump. The brake fluid discharged from the amplifying piston is supplied to the W/C via a first pipeline. The brake fluid discharged from the pump is supplied directly to the W/C via a second pipeline. First and a second control valves select the first or the second pipeline as a pressurizing path to the wheel cylinder.

Abstract: A hydraulic booster is provided between a M/C pressure and a W/C pressure. The hydraulic booster is composed of a pump and an amplifying piston amplifying the brake fluid amount discharged from the pump. The brake fluid discharged from the amplifying piston is supplied to the W/C via a first pipeline. The brake fluid discharged from the pump is supplied directly to the W/C via a second pipeline. First and a second control valves select the first or the second pipeline as a pressurizing path to the wheel cylinder.