When you turn on your defroster you smell antifreeze?

If you smell antifreeze when turning on your defroster, it may indicate a leak in the heater core, which is responsible for heating the air that enters the cabin. The heater core uses hot coolant from the engine to warm the air, and if there's a leak, coolant can escape and produce a sweet smell. This situation should be addressed promptly, as low coolant levels can lead to engine overheating and more serious issues. It's advisable to have a mechanic inspect the system to prevent further damage.