A furnace that blows cold air or short-cycles needs assessment. A gas odor, propane alarm or suspected carbon-monoxide exposure changes the priority. For gas odor or a propane alarm, evacuate without operating switches, the engine or generator, and get emergency or gas-supplier help from a safe place.
For fire or suspected carbon monoxide, leave for fresh air and call 911. Do not re-enter until responders allow it. Routine service details can wait until any immediate hazard has been addressed.
