With the system set to heat, when the set point temperature is raised
or lowered past the room temperature, the thermostat will make a soft
click sound within about 5 seconds. Usually the sound indicates correct
thermostat operation. If the heat does not come on after raising the
temperature and hearing the click, check the fuses or breakers, make
sure the furnace is switched on, and verify the blower compartment door
is closed properly.