Unfortunately, it seems our furnace stopped working a couple of days ago. I can get the fan to work if I set it to "on" but not "auto". And even if the fan is blowing in the "on" setting, the air never warms up. I've tried playing with the thermostat and resetting the whole thing a few times from the circuit breakers without success. Beyond this, I don't know what else to try.

GAS FURNACE? If so what type of ignition, Standing pilot which has an actual flame that stays lit all the time, a hot surface ignightor which is a plug lige device which glows cherry red and ignightes the gas or direct spark which is a high voltage spark that sparks between two electrodes. Or do you have a heat pump which is Electric and uses the outdoor unit to heat and cool.