An oily, smoky smell was blowing into the cabin of my 2002 Blazer a few days ago, and white vapor was coming out of the air vent. The defrost vents were not clearing my windshield. I thought the heater core might be going, but there was no leak. Mechanic went over it and found nothing wrong, no leaks in the coolant system, and says he never saw vapor. Same day he gives me the Blazer back, there's vapor and stink. I go over the whole engine compartment and discover the blower motor enclosure is cracked on top and pieces fall off when I put minimal pressure on it. (Looks like water leaks onto it because the weatherstripping is worn out right over the blower motor cover.) To test it, I cover the cracks with duct tape. The smell is diminished and the defrost works better. Can I replace just the blower motor cover? If so, how difficult is it going to be to remove and replace?

 

You can take a box cutter and cut through along the scored outline of the cover to remove it and replace it with one from a junker (if it's not deteriorated). Seal the new one along the edges with black RTV.