You have either a cracked heater core or bad heater hoses that are allowing antifreeze to enter into the vehicle............
Your heater core has failed.
The air is off.
Most of the time it is caused by a hole in the heater core, do you smell a sweet smell? The sweet smell would be the antifreeze.
heater core
The "fumes" are more than likely antifreeze from a leaky heater core.
Most likely the heater core is leaking. Has to be replaced.
More than likely the heater core is leaking.
The most common signs of a heater core problem is either leaking antifreeze or a mist coming from the air vents. There will also be a sickly sweet smell in most cases.
heater core is shot and you have to get a new one
heater core, tough job.take it to a qualified auto technician
replace? why not fix it?