At some point today, the furnace stopped coming on periodically to blow heat, even though the house was noticeably cooling off. After a few hours, we tried switching the setting on the thermostat from “Auto” to “Fan,” and air did start coming through the vents, but only cool air, even though the temperature on the thermostat was set high.
We tried setting the heat extra high in case some kind of temperature gauge in the system may have been off-kilter; we tried flipping the switch in the circuit panel off and on. Nothing is making any difference.
Any home-repair-knowledgeable people out there have thoughts on what might be happening?