"Most people don't understand [and when they] put a new system in think, 'I’ve got a new system, so I won't have to maintain it,'" Conover said. "Well, there's nothing greater from the truth than that, because manufacturers require you to have regular maintenance and to have record of that. If you would ever have a warranty claim, that manufacturer has the ability to ask you for those service records. So not only does it make sense from a perspective of the longevity of it, but if you have a warranty, you want to make sure you keep it intact."
2Be sure the furnace’s circuit breaker is on or that its fuse has not blown. Check both the main electrical panel and any secondary subpanels that supply power to the unit. If the circuit has blown or tripped, reset the circuit breaker by flipping it all the way off and then on again. Or replace the fuse. If the circuit blows again, there is probably a short in the electrical system providing power to the furnace. For this, you may need to call an electrical contractor.