When a furnace stops heating there are many things a home owner can do to fix the problem before calling in a professional and paying lots of money

first thing you should check is your thermostat and make sure it is set properly

heating

heat/cool/heat/off switch is set to heat
auto/on does not affect heat call -on fan will run all the time and change speeds with heat or cooling call -auto fan only runs on heat or cooling calls
temperature call must be higher then the room temperature where the thermostat is located (when house is cold, by adding heat near the thermostat it may cause the furnace not to come on due to that heat. the rest of the house will be cold
digital thermostats will use battery’s make sure they are above 1.5 volts. Do not use rechargeable battery’s, as they are designed for cameras and are only 1.2 volts.some digital thermostats do not require battery to run, because they are getting power from furnace on “C” terminal . Some any time “C” terminal is connected the battery’s are only good if you remove thermostat from wall for programming . Battery’s will leak if left for long time it is still recommended to replace battery’s every couple years. Battery’s should be tested yearly
Cooling

similar to heating except heat/cool/off must be set to cool
temperature must be set below room temperature

Thank you for visiting my blog I would appreciate any feedback I can get, Please leave a comment on whether my information has helped you. I am always interested in more topic to write about, so feel free to leave a comment asking about anything related to HVAC-R(Heating, Ventilation ,air conditioning, refrigeration).

Thanks for reading my blog
Gary