If your furnace fan isn't starting, you may have an issue with the wiring or the motor. It's possible that the thermostat is to blame, but only a professional HVAC technician can accurately diagnose and fix the problem. To start, locate your home's service panel or fuse box in the garage, basement, or outside the house. Most homes have their ovens connected to their own circuits.
A power outage, storm, or power surge in your home's electrical system can cause the furnace circuit breaker to trip or the fuse to blow. Before you do anything else, rule out energy as the cause by checking your oven's fans. It's incredibly frustrating when you turn on the boiler only to find that no heat is coming through the vents. You may have experienced it working after running the fan for a while, but now it won't turn on after you turn on the oven.
When filters get dirty, air flow is restricted, which can cause your oven to work harder than necessary. In this case, even if the oven is actually blowing air, a clogged filter will prevent it from entering the ducts. If the heating temperature is too high and the oven doesn't turn off after adjusting the thermostat, it could even overheat the system and damage individual components. Every modern oven is equipped with a safety lock that will activate if it gets too hot, and a blocked air filter can cause it to overheat, shut off on its own, and give you the impression that your oven isn't blowing air.
If your oven fan isn't turning on, make sure that the arrows on the air cleaner are pointing in the right direction. In most cases, when you have an issue with your oven motor fan, it's because the motor has overheated for some reason. Darrell If the fan motor runs in heating mode, I don't think that if it doesn't start in cooling mode it's due to a fault in the fan motor condenser. Before moving on to more complex problems with oven fans, check your home's vents to make sure they're open.
Ovens and their corresponding thermostats are designed to turn off when they reach the desired temperature in a room. In this system, not only does the heat zone valve open and close warm water but also powers the ventilation unit. If the fan motor doesn't start up, then your oven will overheat and its high temperature limit switch should cause its burners to shut off.