In a refrigeration system, a first non-inverter compressor (2B) backs up one of an inverter compressor (2A) and a second non-inverter compressor (2C) by switching of a third four-way selector valve (3C). The refrigeration system includes: a suction pressure detection section (81) for detecting the suction pressure of the first non-inverter compressor (2B) after the issue of a switching command to the third four-way selector valve (3C); a command holding section (82) for, when the detected pressure of the suction pressure detection section (81) becomes lower than a predetermined value, determining that the third four-way selector valve (3C) has malfunctioned and holding the switching command; and a compressor standby section (83) for, upon the command holding section (82) holding the switching command, stopping the first non-inverter compressor (2B) and putting it into standby for a predetermined time.