Chevy & GMC Vans

This may be a stupid question, but I'm new here...

I just bought a 2000 GMC Safari with low miles, so it has been sitting. When I turn on the AC/heat all kinds of crud comes out out of the vents. I have reason to believe something made a nest in my cabin air filter, so this will need to be replaced and cleaned out.

So I have the following questions: Where is it located? If it is not obvious, how do I access it? Any other recommendations or suggestions for this situation would also be appreciated.

Thanks.

edit: I am assume it is up above the passengers feet, under a black cover secured by 4 hex screws.

I don't think these vans ever came with cabin filters. Can't find a parts listing for any year on www.RockAuto.com. IIRC, the air intake is located at the cowl.

FYI, Above the passenger feet is the heater core.

nope, no cabin air filter. Need to take apart the cowl and get the crud out or just live with it.

Fair enough... For now I'll just blast the vents for a while then vaccum everything.

I found a lot of conflicting information with my internet searches. Some said there was a cabin filter, some said there wasn't.

Could it possible have been a flood car, lot of them around.