In this segment, HVAC specialist Derek Cole explains why homeowners in humid regions like southeastern North Carolina should set their HVAC system fan to AUTO rather than ON. He describes how leaving the fan continuously ON pulls moist outdoor air into the home, leading to excess humidity, dehumidification challenges, and visible black debris from the grill. Cole contrasts this with dry‑climate practices where an always‑ON fan is acceptable. He also notes that a constantly running fan can cause the blower wheel to become dirty and unbalanced, reducing airflow and creating additional issues. The recommended solution is to keep the fan on AUTO, ensure the blower wheel is clean, and address any imbalance if present.
Chapters
The challenge is that, yeah, even though it's 70 degrees here, humidity is like 80%, so you're just bringing that moist air into the space and, and you want to dehumidify and get that out. In our part of the country, southeastern North Carolina, you really shouldn't do that, like ever. You want to always have the fan on auto, otherwise you're going to cause a humidity moisture problem in your house. So we always recommend it be on auto. When we have installed the new system, I know I've been to two personally myself where the homeowners were putting it on, on, on for the fan, and black stuff was coming out of the grill, and they're like, what's going on? And we get there and the fan is on, on. Okay, we'll put the fan on auto. The challenge is that, yeah, even though it's 70 degrees here, humidity is like 80%, so you're just bringing that moist air into the space and, and you want to dehumidify and get that out. So you want to leave it on, on. Um, now up north, uh, they have their fans on. I think even like Illinois, and they might leave it on all the time. And it's funny because it's dry is a dry climate. That's not us here in North Carolina, so leave it on auto. I've never heard of it causing an imbalance of air problem. Not sure what's going on there. What can happen with that fan is the blower wheel will become unbalanced, and that might be causing some of your issues there. So, okay, let's check it out. Dirt, debris, and everything can get on that little blower wheel, and it will have trouble pushing the air into the space. So make sure that it's clean, and it will be balanced if it's clean. If it's not balanced, then fix it so it's balanced.
