I own a 2002 E320 that has 41000 miles on it. I've owned it for three weeks and noticed a burnt crayon smell coming from the dashboard/vent area. I took it in to mercedes service dept so they could find the problem. They called me and said they could not find anything wrong. Typical. The smell is there.
Could it be mold? How can I get rid of this smell?What do you think about using a ozone generators if it's mold.

GM used to sell a foaming AC cleaner to spray into vents & the AC system. it was wicked stuff and had a residual effect (prevents mold).

Be sure your drain is not clogged (I've heart compressed air blown in from beneath the car works) so the condensate from your AC can get out. Does it leave a puddle on the ground like it should while the AC is on?

Try search for your particular year/model.

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Remove the pollen filters and blast some air through the system. I'd also be concerned that the fan might be burning, so check the regulator.

Pollen filters is another name for cabin filters, correct

Just purchased a 2009 S550 with 4K miles and have experienced the same crayon smell in the cabin. After hours of research, cleaning the AC system and removal of seats and carpet I found the smell! It's the same as yours; it's the sound deadening insulation Mercedes uses. I have seal coated the material which has stopped the odor by 95% but the bottom of the rear seats have been permeated with this smell as well so I have repeatedly sprayed them with a commercial odor remover to see if this will cure the problem. Only time will tell. I have talked to Mercedes Corporate and 3 different dealers and nobody is admitting there is a problem with past vehicles. I found this very hard to believe since it's seems to be a common complaint on the internet. Are they trying to keep it from causing a major recall? This is bad stuff which is a major health concern. Even though my vehicle is covered under full warrantee I have hesitated taking it to a dealer because it's a 3 hour drive one way so I decided to do some investigation on my own because most dealers in my experience turn a deaf ear when it comes to a subjective complaint.

If you don't replace your carpet and panels that come in contact with this sound deadening product then you will continue to have residual crayon smells. Also they have used this crayon smelling product in areas like the firewall which I could not get at to use my seal coat so I suspect that the odor will continue to some degree.

Good Luck

How dreadful for such a costly and nearly new car (having to dismantle and use a spray on the interior)

... I have found the smell of my 1980s Mercedes very distinct and very pleasant.... they all smell the same.