Smoke pouring out of all air vents when the temp dial is not on Max cold/blue

[VWGoodliffe]

Hi,

Whenever I turn the heat dial up from anything that isn't max cold/blue smoke pours from all open air vents and completely clouds up the windscreen. It smells like a fluid burning. After driving for a while and with all the air vents on full blast and max heat the smoke eventually stops and won't happen again, but then when I stop and turn of the ignition for more than 10 minutes it will start again pouring out smoke. I thought it would eventually stop but it's been going on for a month or so now.

any ideas?

[zollaf]

is it losing coolant. probably a leaking heater matrix.