Abstract: A time variable thermostat comprising, a housing, a clock connected to the housing and having a shaft which is rotatable with time and a disc connected to the shaft for rotation with the shaft. The disc has a plurality of circumferentially spaced slots each extending radially of the disc. A temperature responsive switch has an actuator movable with a change of temperature and the switch includes contacts which are closed and open depending on a position of the actuator. A double control arm is connected to the actuator and is movable with respect to the housing about a center of rotation and a pin slidably mounted to each slot and having a stop portion extending beyond the disc against which the control arm is engageable to influence closing and opening of the contacts. One arm includes a pin engagement portion movable in an arc with movement of the arm about the center of rotation.