Fogged Windows, Heat/DeFrost Not Working and a Funky Smell

Yesterday I got into my car and it smelled sort of bad. I then began driving, it was cold and the windows were fogging up so I turned on the defrost. That did nothing, in fact it got progressively worse where I had to turn the dial to cool. After driving 50 miles home, I discovered if I turned on my heat/defroster, a smoky bad smelling substance came out of the vents. Any ideas to what is wrong? Is it heater core? How much is this to replace? Any help would be appreciated. Thanks. I drive a 2000 Subaru Outback with 120K miles on it.

Mouse ?
No kidding, here at my Ford dealer we’ve found many a rodent’s nest, and many rodents, inside the heater housings. The debris can keep the damper doors from moving properly.
I guess they really do like those squirrel cages.

The heater core is a possibility if the coolant wasn’t changed as often as it should be. Was the coolant changed ~every 30k? If it was, the heater core is probably not the source of the problem.

If the heater core was the problem, the smell would likely be more of an oddly sweet smell, or a smell similar to hot coolant. And, you would have an oily film on the inside of the glass–particularly the windshield. If there is no oily film, then you probably don’t have a heater core problem.

I am not sure if the coolant was changed every 30k, but I did get all of the recommended services for the car. Do you of anything else that else could cause the issue?

It would help if you could describe the smell. Do you smell it outside the car or only inside? Sweet smells are coolant and indicate a coolant leak (the windowing also points this way). Moldy smells tend to indicate a blocked drain in the A/C or the area under the vents in front of the wind screen.

Good Luck

I smell it inside. The care smelled normal on the outside after my drive home. It is more of a sweet smell. It is definitely not a moldy smell.

A sweet smell does seem to indicate a bad heater core.