A refrigeration system for cooling air having an evaporator; a compressor; a control for establishing ON periods and OFF periods of the compressor; at least two motor-driven fans positioned to force air over the evaporator; and a control system for the evaporator fans to cause fewer of the fans to run...http://www.google.se/patents/US4137057?utm_source=gb-gplus-sharePatent US4137057 - Refrigerating systems with multiple evaporator fan and step control therefor
