Abstract: The present invention provides for a control for activating and deactivating heating, cooling and fan recirculate modes having an interval timer switchable between a timer on (TON) state and a timer off (TOFF) state, both the TON and TOFF state durations are variable according to comparisons between room temperature and a set point temperature of the control and the control activating the fan recirculate mode when the room temperature deviates from the set point temperature of the control. An interval spacer is provided to prevent back to back fan on states.