**Work Performed:** Initial call for no fan operation from the furnace. Upon inspection, found the 5-amp low-voltage fuse blown. Performed diagnostic testing to identify the cause — traced the fault back to the air conditioner contactor, where the coil windings were shorted out. Visible bubbling and damage confirmed the contactor has failed and is shorting the low-voltage circuit. Replaced fuse and confirmed that the furnace is still capable of operating in heating mode. **Findings:** * 5A low-voltage fuse blown due to shorted contactor coil in the air conditioner. * Furnace operational for heating; air conditioner contactor requires replacement. * Outdoor condenser coil heavily clogged with debris and needs thorough cleaning. * Furnace also due for maintenance. * Tenant had inserted batteries into the thermostat during troubleshooting. The thermostat is wired with a **C-wire**, so batteries are not required; however, this did **not cause any issues** and did not contribute to the s