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.
Yes. You should expect to pay a diagnostic fee to cover the cost of the technician's visit, the diagnosis of your air conditioner's problem, and a quote for the repair options. You will be advised of the issue along with recommended options to correct it, which may include a system replacement if your unit is old or significantly damaged. If you decide to replace the system, the diagnostic fee will be credited toward your replacement purchase.