1999 Boxster heater core

[Kale]

I have a 99 Boxster and have the smell of coolant periodically when the heater temperature is above 75. The AC is seldom on, the carpets are not damp, no coolant leaks or drips internally or externally, however the windshield doesn't defrost at warmer heater temps. I doubt it's the AC condenser drain since the AC is never on and there is no coolant smell when the AC is on. The sweet smell of coolant is instant at full fan speed with hot air blowing upon engine start. A bad heater core would result in internal leaking....which there is none. Does this sound like a heater core.