Common problems with Comfort furnaces include a flashing motherboard, unresponsive buttons and LED lights, and the fan not working. Another problem that may occur with a Comfort furnace involves the heating elements not heating up enough.
If the motherboard is flashing or constantly reading "888888," then the furnace needs to be relocated to a grounded outlet, and the motherboard needs to be reset. The motherboard may require replacement if this does not solve the issue. If the lights and buttons are not responding, that may also mean the motherboard needs to be replaced.
If the fan stops working, check the fan limit switch for any type of malfunction. The fan needs to be replaced if the fan limit switch is still working properly. A whining or clicking noise coming from the fan means that the bearings are worn out and require replacement.
Heating-element issues are also common and easy to diagnose. If the heating elements are not getting hot enough, check the connections and tighten them if necessary. The infrared heater needs to be above 170 degrees Fahrenheit, otherwise it has burnt out. Check the heater with a meat thermometer to test the temperature. If the heating elements are not working at all, an authorized repair person may need to resolve a problem with the motherboard or the transformer.