You turn up the thermostat and the induced draft fan fails to start. This is most likely to be a problem with the?

If the induced draft fan fails to start after you turn up the thermostat, the most likely issue could be related to the fan motor or its electrical supply, such as a blown fuse or tripped circuit breaker. It could also be due to a malfunction in the control system or a safety switch that prevents the fan from operating. Additionally, check for any blockages in the venting system that might prevent the fan from functioning. Troubleshooting these components will help identify the root cause of the failure.