A simple, reliable, compact, low cost and low power cooling system is disclosed. The cooling system is especially suited for an electronic equipment enclosure which is located out-of-doors. The cooling system runs on community AC power which is converted to DC. If community power is disrupted, the cooling system takes power from back-up batteries. If a compressor of the cooling system drops to a temperature of 0° C., a heating subsystem including a conduit loop that runs around the compressor and into the equipment chamber of the enclosure for transporting a heat transferring fluid, is activated for transferring heat from the equipment chamber to the compressor. A closed conduit loop is used to pump a mixture of ethylene glycol between the vicinity of the compressor and the interior of the equipment chamber. In this way, heat generated by the equipment to be cooled is transferred to the compressor to heat the enclosed refrigerant and the equipment is simultaneously cooled. The power required by the system is very low, because the system is compactly constructed and the arranged for maximum efficiency.