coolant is always flowing through the heater core, so if its leaking it will fog up the air box, some of which can leak through the blend door and into the AC stream.

but - if you turn the heat on, which opens the blend door, then the fog will be more pronounced.

if it is leaking, then as said, you can reroute the heater hoses in the engine bay to bypass the heater core. you'll have no heat - but it will at least be driveable until you can fix it.

 

If you put your defroster on high heat (night or early morning) and see if a FILM develops. If it is JUST condensation, it will wipe away without smudges. if it is coolant, it will smudge.

in my 1996, it smelled like pancake syrup.

 

i'll try the defrost and heat first thing in the morning and see what happens.

thanks guys!

 

aight. so the heat works like no other.....but no smell and no fog coming out nor on the windshield.

maybe there really is mint skoal down in the vent

 

could be mildew.

turn on AC (not max) so its drawing in fresh air through the cowl and leave the doors open. get some good smelling lysol like 'fresh linen' or something you can stand and spray a lot of it in the cowl. you'll see it being drawn in and it'll kill the mildew and improve the smell. the truck will also smell like lysol for awhile so make sure its a smell you can tolerate.