Patent ID: 6983794

Claim:
A heat exchanger unit adapted to be arranged between an indoor space and an outdoor space, and that can perform heat exchange and ventilation, comprising: a heat exchange element; a supply air passage that is routed via said heat exchange element; a supply air fan disposed in said supply air passage; an exhaust air passage that is routed via said heat exchange element; an exhaust air fan disposed in said exhaust air passage; a temperature sensor that detects an outside air temperature of said outdoor space; and a control unit operatively coupled to said heat exchange element to execute a first freeze inhibit control mode if the outside air temperature falls below a first level, and a second freeze inhibit control mode if said outside air temperature falls below a second level, which is lower than said first level, said control unit inhibiting freezing of said heat exchange element in said first freeze inhibit control mode, said control unit intermittently operating said supply air fan in said first freeze inhibit control mode, and intermittently operating said supply air fan and said exhaust air fan in said second freeze inhibit control mode.