Cheap Air Purifier

I bought a used air purifier off of craigslist.com that worked fine. I wasn’t sure if it would help my allergies so I thought I’d go the cheap way first. Well once I got the thing home and turned it on, it started giving off this weird smell. I’m assuming it’s just the smell of the guy’s house. It doesn’t stink but is really distinct and bothers me!!!! It’s not the filters, though. I cleaned them and smelled them and they are fine. It’s the actual unit. Anything I can do??? Will it eventually go away????

I’m not familiar with air purifiers. Do they run on air or water? If it is water, try running white vinegar in it instead of water. That should take away the smell.