Many homeowners begin by searching for furnace repair harbinger when they notice weak airflow, unusual noises, or frequent cycling. If the system is short cycling, blowing cool air, or struggling to keep temperature, write down what you observe and when it happens. If you smell gas, hear loud grinding, or see repeated shutdowns, it is safer to stop running the system and request service. Depending on what is found, the solution may involve furnace diagnostics and repair, thermostat repair and replacement, air handler and blower repair, or HVAC tune-up and maintenance to restore normal operation. Routine maintenance can also reduce surprises