I have my thermostat set at home at 70 degrees. My furnace runs until it's about 66 or 67 degrees and then shuts off. I had this problem when the furnace was installed a few years back and know it requires a quick adjustment because the service tech was in and out in just a few minutes. Does anyone know how to resolve this issue? Would you mind sharing that info with me if you do so I don't have to pay $80 for a minor adjustment?