Abstract: An apparatus for supplying a cooling liquid to a condenser of a refrigeration unit. The apparatus comprises a conduit for passing the cooling liquid from a source thereof into thermal communication with the condenser, and a valve to regulate the flow of liquid through the conduit and having an open position allowing the liquid to flow through the conduit. The apparatus further comprises an electronic control for use with a source of an electronic signal, including an electronic switch having an open state in which the electronic signal does not pass through the switch, a closed state in which the electronic signal passes through the switch, and a trigger wherein, when an electronic signal having a predetermined magnitude passes to the trigger, the switch changes from the open state to the closed state.