It seems like the furnace is igniting, but there's an issue with the heat distribution. Given that the fan works independently of the heat, it's likely not a problem with the fan itself. You might want to check the limit switch, which could be preventing the blower from turning on. Additionally...
It's possible that there is a misconfiguration or malfunction in the furnace's control system. Check the thermostat settings to ensure it's properly configured for a two-stage system. Additionally, inspect the wiring and connections between the thermostat, furnace, and blower to rule out any...