I was called to a home to check on a furnace that was not working. Upon arrival, I found that the furnace was running good, no issues, and ready for the winter. I checked the thermostat and found that it was set to 65 degrees, which was the correct temperature. I adjusted the thermostat and tested the furnace to ensure it was working properly. I also checked the air filter and found that it was dirty, so I cleaned it and replaced it. I also checked the venting and found that it was clear and not blocked. I tested the furnace again to ensure it was working properly and left the home.