Fan doesn't come on, in auto or manual, when look at indiactor light, is always off, unless I flick the safety swtich, than it flASHES ONCE & goes off again!

Fan not coming on, no idicator light present, unless you flick the safety swtich- flashes once at that point & than goes off again!

Many possibilities. Bad motor, bad board, bad thermostat or thermostat wire. Light flashes at least tells me there is 24 and 120 volts at furnace.