In this video
- Clean filters about every 3 months and the coil about once a year to keep airflow strong
- A clogged coil creates negative pressure that pulls in outside odors through the condensate drain line
- Foam coil cleaner (about $10 a can) is self-rinsing — spray it on, wait roughly 15 minutes, then wipe and reassemble
- Spray up and down along the direction of the fins, and use the can's spray-pattern dot to get better coverage between tightly spaced fins
- A side-by-side comparison shows a cleaned section of coil next to an untouched, debris-clogged section
Questions this video answers
How often should I clean my mini-split's filters and coil?
Clean the filters about every three months and the coil about once a year. Dirt builds up fast enough in just six months to visibly clog both.
Can I clean a mini-split coil myself without removing the unit?
Yes. You can pop off the front cover, unclip the filters, and spray foam coil cleaner directly onto the coil while it stays mounted on the wall — no disassembly of the unit is required.
Why does a dirty mini-split coil cause bad smells in my house?
A clogged coil restricts airflow and creates negative pressure inside the unit, which pulls air in from other sources, including the condensate drain line, bringing outside odors into your house.
What kind of cleaner should I use on a mini-split coil?
A foaming, self-rinsing coil cleaner from a hardware store, around $10 a can, works well. Spray it along the direction of the fins and let it sit about 15 minutes before turning the unit back on.
How do I clean mini-split filters?
Rinse them with a kitchen or laundry sink sprayer using mild pressure, spraying from the inside first to knock dirt loose, then flip them around to rinse both sides.
What happens if I never clean my mini-split coil?
Dirt keeps accumulating, and the more that builds up, the faster more piles on. Eventually it gets restrictive enough to create negative pressure inside the unit, which hurts performance and can pull odors into your home.
Transcript
Read the full transcript
Todd here. We're going to show you how to check the filters on this mini-split unit. They've been in here for about six months. At first glance, it didn't look like they needed to be cleaned, but let's find out, shall we? We'll just pop this cover up like this, and you can see it comes up a little ways, kind of in the way a little bit. These can be taken loose and set on top. On the sides there are little pivot points; the little arms can push in, and it'll come out like that. That simple.
So, Todd, you're taking it off just so it's a little easier to access?
Easier to access and examine things, because we're going to clean the coil too while we have the filters out. It makes it easier. So first, let's check the filters here. And whoa, look at that! Look at that. Here's a clean one to compare it to. Yeah, and this is only after about six months.
Holy moly, that's a lot of stuff. Okay, so what's the process for cleaning these?
It's real simple. Take this. If you've got a sprayer, a kitchen sink sprayer, a laundry sink, or even outside with a mild amount of pressure, take the nozzle and hit it in reverse of how it collects. It collects on the outside, so you want to blast it from the inside first to knock all the stuff off, and then you can flip it around and rinse it both ways.
Okay, great. See it all come off?
It'll look like that when you're done. Now let's examine this coil. I'm going to move this out of the way for a second so we can see how dirty it is. It looks pretty dirty, and that affects airflow. It'll always keep a little negative pressure on the system and cause it to pull in air from other sources since it won't go through the filters, one of them being the condensate drain line. If that terminates next to anything with odors, it's going to pull those odors into your house. With clean filters and a clean coil, you won't have that problem.
So how often should you clean the coil?
Once a year. And the filters every three months, definitely every three months. Look at what these look like after just six months.
All right, so we're going to grab some coil cleaner we picked up at the nearby hardware store, in this case Lowe's. It's about ten bucks a can, and it's more than enough; you can probably use it two or three times. You just shake it up a little bit, and then it's self-rinsing, you don't need to rinse it, just spray it on.
You're going to get it all over the wall!
And then you spray it on. You've got to get in the grooves really good, like that. It kind of foams up, yeah, it'll foam up and take all the dirt with it, and then it'll disappear. Now look at that side: I go up and down with it, because that's the way the fins run on the coil, and it gets in them pretty good. Usually this stuff has a little wider spray; I don't know why this can doesn't, maybe you need the Home Depot one. But anyway, just go up and down and keep the coil covered pretty good, like that. I'm purposely not going to clean the bottom so we can see the difference when it's done. It'll look like a new coil again, hopefully.
Look at all that dirt. How long before the foam disappears?
It shouldn't take very long, maybe 15 minutes. You can go have a cup of coffee and come back, and it'll probably be ready to go. Then you just put the filters back in and turn it back on. It has a nice fresh scent to it too, so it helps spruce things up. These coils, when you see stuff accumulate on them, it's not just dust. It's all the odors in your house, cooking odors, whatever. It all sticks to that coil. That's why you've got to clean it.
Got it. And what's the consequence of not cleaning the coil?
It just keeps accumulating, and the more you have, the faster it accumulates. It gets to the point where it's very restrictive, and like I said, it causes a negative pressure inside that chamber. Nothing good comes from that. Nothing.
Very good. Okay, we'll check back in 15 or 20 minutes.
All right, Todd, we're back about ten minutes later. What are we looking at here?
That's the section of the coil we cleaned earlier. If you look between the fins, there's no debris, compared to this side over here, where you can see there's debris blocking things up.
Oh yeah, there's a lot of it.
Yeah, that's what you want to get out of there, that's what impedes the airflow. Sometimes with the coil cleaner you have to go over it twice, because the fins are so close together that it's hard for the cleaner to penetrate. If you have to use a whole can, you use a whole can.
So you're going to do another coat, then?
Yeah. There's a setting on these cans, a black dot. If you point that toward the black dot, you get a spray pattern instead of just a straight stream. But even after this side has been washed once, if you look at it, it's still removing stuff. You've got to get in between those fins. Nothing down there, and nothing up there.
And I don't know how it tastes. Do you want to taste it?
Yeah, later.
