Abstract: An auto-control device including a housing mounted on a lift pump, a sensor mounted within the housing by a locating block to detect the temperature of the lift pump, a spring member fastened to the housing on the inside to give a downward pressure to the sensor, a two-line electric wire having one end welded to two contact legs on the sensor and an opposite end extended out of a wire hole on the housing and connected to the power supply circuit of the lift pump, and epoxy resin filled through the wire hole into the inside of the housing, wherein the sensor automatically cuts off power supply from the lift pump when the temperature of the lift pump surpasses a predetermined high temperature level, or turns on the lift pump when the temperature of the lift pump drops below a predetermined low temperature level.