Ducane Gas Furnace intermittent fire goes out, fan still on
Manufacturer: Ducane model # FPBB100A5, manufacter # 9874569843
Age: year is 1995 printed on it
80% efficiency: There is metal flue pipe and a fan I think is draft inducer blower so System: Gas Fired Forced Air Furnace
Fuel: Natural Gas
Sometimes before it reaches the desired temp the furnace fire goes out but the fan continues to blow.
The thermostat is communicating and the fire comes on and then the fan comes on, hot air comes out and if requested temp is reached it all shuts off. But sometimes the fire shuts off before and it just blows.
I had a service check up and they could not find anything wrong. It is intermittent.
Thank you