Q: Smoke coming out of the vents into the cabin compartment.

Hi there. The green ooze that you saw was indeed coolant. The issue could be the heater core hoses or heater control valve is leaking coolant and the ventilation system on your air conditioning system to the open air outside is pulling in the coolant smell. Look around the heater cores hoses area and look to see if the hoses are leaking with worn clamps or if the hoses are split. If the heater control valve is leaking, then the valve may be cracked. Replace the parts that are leaking and then clean off the area with a pressure washer carefully. Then run the air conditioning to see if there is still a smell or if the smell went away. If the smell is still there, I recommend seeking out a professional, such as one from Your Mechanic, to help you trouble shoot the cooling system.