Abstract: A system for controlling a defrost cycle of an evaporator having a sensor module and a control module. The sensor module includes a light source configured to emit light toward the evaporator when activated and to deactivate in response to a lockout signal. The sensor module also includes a light sensor configured to determine an amount of the emitted light reflected by the evaporator and to generate a detected light signal that corresponds to the amount of the emitted light reflected by the evaporator. The control module is configured to receive the detected light signal from the light sensor and to compare the detected light signal to a preset threshold. The control module is also configured to generate a termination signal when the detected light signal is less than the preset threshold and to generate the lockout signal when the detected light signal is greater than the preset threshold.

Abstract: A refrigeration system includes a normal refrigerant path arranged between a condenser and an evaporator, and an assist refrigerant path arranged between the condenser and the evaporator, wherein the assist refrigerant path is activated during low ambient conditions. The assist refrigerant path may include a solenoid valve and an expansion valve arranged between the condenser and the evaporator. The assist refrigerant path may be adapted to regulate the evaporator temperature.

Abstract: A temperature alarm system includes a temperature sensing module and an alarm circuit that are powered by a photocell and a battery that is charged by the photocell. The photocell normally provides enough power to operate the system and charge the battery. When the temperature sensing module senses a temperature that exceeds a predetermined alarm limit, it generates an alarm signal which activates an alarm circuit that generates a visual and/or audible alarm either immediately after the alarm signal is generated, or after the alarm signal has been generated for a period of time. The generation of the alarm signal and/or the alarm causes the system power consumption to increase, so the system begins to draw power from the battery. After the alarm condition is corrected, the system returns to normal power consumption, and the photocell provides enough power to operate the system and charge the battery.