this morning my dash started smoking with a definite burning smell

it appeared to be coming from the temp control unit..
i've noticed lately from the temp controls-
if i have them set to floor i hear this hissing noise

if set to anywhere else a mild hissing

if set to both top and bottom, no hissing

but i get the smell every so once and a while

i know the hissing is a vacuum leak, i am just waiting to get some funds to take care of it, but the smoking??

i hope this isn't expensive.

any idea's on the smoking?

-- Nick
(sugeon generals warning- driving a volvo can be dangerous to your lungs)