A refrigerated soda vending machine includes sensors for monitoring various parameters such as temperature within its refrigerated chamber and for monitoring occupancy in the chamber vicinity. Sensor data is used to determine when to switch between normal and power-conservation modes of operation. In either mode, a cooling system is regulated so that a compressor goes on when an upper internal temperature threshold is reached and off when a lower internal temperature threshold is reached. In normal mode, fans circulate air to maintain a relatively uniform temperature throughout the chamber. During power-conservation mode, the fans are mostly off when the compressor is off. In the absence of circulation, the temperature within the refrigerated chamber stratifies so that a lower cool zone and an upper warm zone can be differentiated. Soda cans are held in vertical stacks so that the lowest cans are located in the cool zone.