Hi, everyone. I'm new here. Thanks for making this forum available and for being a friendly and helpful place to ask and answer. I live in West Los Angeles and we rent a 1970s two-story townhouse with central air. Never had central air before, so I have some questions and concerns about the HVAC. I found the intake grill; it's under the stairs, and when I lifted the grill and the 30-day filter I saw a pretty filthy crawlspace -- a big ol' area underneath the stairs. I expected to see a duct, not a huge empty and dirty crawlspace. So, my first question is: Is that air under the crawlspace what is getting sucked into our HVAC and then sent back out through the outtakes? I woulda thunk there was some sort of obvious duct in there. Once I get an answer for this, I can start figuring out how to assess whether the outtakes are delivering acceptable air quality and if not how we can address that issue. Until then, we'll be using the space heaters. Thanks in advance for any help you can provide.