a refrigeration controller is provided which thermostatically controls a refrigerated compartment temperature . a heated evaporator is provided within a certain wattage range to accelerate defrosting . the controller maintains the compartment temperature within a certain operating range ; if the compartment temperature rises above a certain preselected maximum temperature , the controller activates the compressor and a blower to circulate air over the evaporator to reduce the temperature of the compartment . the controller provides a defrost loop which is periodically activated which controls the compressor , evaporator and heater cycle during defrost . if , during defrost , the evaporator reaches a maximum temperature , or if the food compartment temperature rises above a certain maximum , the heater is deactivated . an evaporator precool loop is provided which activates the compressor without activating the blower , thereby cooling the evaporator before hot air is allowed to circulate in the compartment . the controller is also physically separated from the main circuit board and mounted on a removable modular refrigeration unit , thereby isolating the controller from the main circuit board and protecting it . the invention also provides for reprogramming of the temperature ranges and command defrost and cooling cycles by a remote main circuit board .