Green light indicator for cold water comes on periodically went none is used. Is this normal? Wondering why the cold water doesn't stay cold.

It is normal for the unit to attempt the cool the water even when not being used. While the cold water reservoir is well insulated, it cannot completely prevent the temperature from rising. Similar to a refrigerator, the thermostat is set to keep the water within a specific temperature range. If the water temperature rises above the range, the compressor turns on to bring the temperature back down to the lowest setting. Having the unit near a source of heat or in a warmer room may cause the cooling system to run more frequently.