Derek Cole explains why AC units freeze and homes get weak airflow. A dirty air filter or fouled blower wheel restricts airflow, and duct leaks can cause 20 to 30 percent of airflow loss. Low refrigerant also freezes the evaporator coil.
Questions this video answers
The main causes are restricted airflow—often due to a dirty or clogged filter, a dirty blower wheel, or leaky ducts—and low refrigerant levels. Both conditions can lead to the evaporator coil icing over and should be inspected by a professional.
Poor airflow can stem from the same issues that cause freezing: a dirty indoor blower motor/wheel, clogged filters, or duct leakage. Cleaning the blower wheel, ensuring filters are clean, and sealing duct leaks are key steps to restore proper airflow.
Chapters
Hey, on this episode we're talking about my unit is freezing and we're talking about airflow. You ask your comfort and energy questions and they get answered. This is the Ask Derrick Cole Show. Hey, this is Derrick Cole. Welcome to episode 78 of the Ask Derrick Cole Show, answering your home and energy questions. And as we're getting into cooling season, we're getting more of those questions. So here we go.
What causes my unit to freeze over in cooling?
A couple things could be happening when that goes on. The main cause is usually airflow. So you need to check your filter to make sure that it's clean, it's been replaced, it's not stopped up. That way air cannot get through. If airflow is restricted in any way, it's going to cause that to freeze over. You'll see kind of like what happens in your freezer when you have too much ice going on there, right? You see that frozen over coil. Same thing happens with your unit. Also, a thing could be happening, especially when you go into cooling season, that you'll notice is it's low on refrigerant. We kind of hit refrigerant pretty hard last episode, so go back and watch that. But if you're low on refrigerant, it will also tend to freeze over, and you'll start seeing that at the outdoor unit. That little line that goes from the outdoor under your house or in the attic, you'll start seeing that freeze over. That's an indication that you're having that kind of challenge as well. So a couple of things going on. It could be airflow, it could be refrigerant. Either way, it's not normal and it should be checked out.
There's not much airflow in my home when my air comes on. What causes that problem?
Poor airflow. It could also be going back to the First question, if your unit is freezing up, you could have poor airflow as well. A couple things could be side by side there. You want to check that to make sure it's not freezing over for the poor airflow. Another thing is when you have a dirty unit, a dirty indoor blower motor and a dirty wheel, see what happens when you have the blower motor which pushes the air in the house, right? It pushes the air in the house and uses what we call a squirrel cage, but it's a blower wheel. That actually pushes the air in. So if you look at the blower wheel, it's kind of like a cup. It has all these little fins on it all around the circle, and it's taking air and it's throwing it and it's pushing it. All right, it's pushing it in the house. So when that becomes dirty, when you have dirt and dust buildup on it, it becomes flattened. So now you're trying to push air like this. Obviously not as effective as the cup, right? So one thing to look at is make sure your unit is clean. We go to quite a few systems where our blower wheel needs to be taken out, taken outside, cleaned, sprayed down, dried off, and then put back inside because there's so much of a cake of dirt and dust on that blower wheel that it's gone from a cup to straight, and therefore it's not catching the air, it's not throwing it back in the house. So Outside of that, in the freezing unit, check your duct system to make sure that's happening as well. Again, the EPA says that 20 to 30% of your duct air loss is from the duct system because of leaks. So make sure all that is sealed up. We have technology available now that can actually seal your duct system down to almost zero. Of leakage. So check that out, make sure. But really the big cause outside of airflow is a dirty blower motor, dirty blower wheel. So again, when that air cannot anymore— when the air cannot get through to that inside the house to the duct system, that's going to cause an airflow problem. So make sure your unit is clean, make sure your duct system is sealed, and make sure you don't have that freezing going on with your system. So if something feels off, if something feels like it's not normal, you know, go out there and just kind of look it over, check it out, see what's going on. And always, you know, call us if you need us. All right, so that's episode 78. That was kind of quick. So if you have any questions, be sure to hashtag #AskDerekCullen. Get him on the show.
