Coolant smell when defrost is engaged in hot setting

RUB YOUR HAND ON THE FRONT PASSENGER SIDE CARPET, IT MIGHT BE WET. IF IT IS IT'S PROBABLY THE HEATER CORE. THE SMELL IS A GOOD SIGN TOO.

On first start up there is no heat until the car warms up so the defrost is blowing colder air, could be problem.
but also could be heater core leak, check floor under the dash for wetness, or the evaporator case for wetness.
check coolant level in engine bay.
worst case scenerio there is a bad window seal

Just has the last tech said heater core has a leak this will be a little exspensive to fix thanks for your question

Heatcore is shot and needs to be replaced

U HAVE A LEAKING HEATER CORE.

There is only one possible cause to this easily diagnosed symptom. Any mechanic will tell you: the heater core is leaking. This is why the steam is rising up to the windshield, and why you are smelling coolant. Your heater needs to be replaced. There is not quick fix, just replacement. Hope you can get this done soon. Heater cores are nice to have during winter weather. Steamy windows aren't easy to see through, and are hard to defrost! Thanks for the question. Good luck. TT