A fan controller reduces the percentage of time that fans used in a heat exchanger of an outdoor cabinet that houses electronics and power source must operate to provide required cooling to the electronics and power source. The fan controller can also reverse operation of a fan of the heat controller to help reduce clogging of air intakes as well as to clean the interior of the cabinet. In an embodiment, the controller operates the fans in the heat exchanger according to operating temperature ranges. Thermostats can be used to provide the operating temperature ranges. Depending on the state of the thermostats and the ambient temperature, the fan controller causes one fan to operate in the reverse direction while the other fan is idle, causes one fan to operate in the forward direction while the other fan is idle, or causes both fans to operate in the forward direction.