Refueling screw compressor

A refueling screw compressor comprising:

• a compressor body that compresses air while refueling a lubricant;
• a suction filter that removes foreign matter, dust, or the like in suction air of the compressor body;
• a suction throttle valve that suctions the air from the suction filter to adjust a supply of the suction air to the compressor body;
• an oil tank that stores the lubricant separated from compressed air;
• an oil separator installed downstream of the oil tank, in which a filtration element is mounted;
• a first cooler installed downstream of the oil separator to cool the compressed air;
• a first air release electric valve connecting a space of the oil separator and an upstream space of the suction throttle valve;
• a second cooler connected to the oil tank to cool the lubricant;
• an oil filter provided in a circulation path circulating the cooled lubricant to the compressor body again, to prevent contamination of the lubricant;
• a cooling fan that cools the first cooler and the second cooler;
• an operation panel on which an operation mode is input;
• a control unit that controls an operation of the refueling screw compressor;
• and
• a discharge electric valve that shuts off a supply of the compressed air cooled by the first cooler,
• wherein when a diagnostic mode is selected by the operation panel, the control unit performs control such that the discharge electric valve is closed to shut off the supply of the compressed air, the first air release electric valve is opened to connect the space of the oil separator and the upstream space of the suction throttle valve, and the suction throttle valve is opened to suction the air from the suction filter and to supply the suction air to the compressor body.