Cleaning a minisplit
- Jen Jo
- Nov 21, 2024
- 6 min read
Updated: Mar 30
Those of us who are super sensitive to mold and bacteria may find we need to clean our minisplits more often than “regular” people. My family has found we need to clean them three times a year:
Beginning of summer, before turning them on cool mode for the first time, to remove all of the dust accumulated over the winter
Middle of summer
End of summer, to start fresh before we turn them on heat mode again.
We go by symptoms and smell. When the minisplit is clean, it smells like nothing. When it’s time to clean it, it has kind of a sour smell to it; the same smell your car air conditioning gets when it gets dirty. For me, a dirty minisplit also kicks up my Long COVID/Mycoplasma/Whatever it is chronic cough. When I get that, it’s time to set aside our other tasks and tackle the minisplits. I’ve never seen visible mold of any kind in our minisplits. My body tells me it’s time long before any mold or bacteria is actually apparently.
You can hire people to clean minisplits. We did the first time we cleaned it, and I would suggest that you do, too; the first time. When you make the appointment, tell them that you’re wanting to hire them to not only clean your minisplit, but also teach you how your particular unit comes apart so that you can clean it yourself next time. Keep calling until you find someone who is willing to do this.
It’s been a while since we had this done, and my memory is hazy, but I think we paid about $300 for the company to come out and clean one head. Also, they insisted on using their soap, which I reacted to almost as much as I was reacting to the mold. So we’ve been doing it ourselves ever since.
I’m going to tell you in this post how we do it, using easily-obtainable supplies and equipment. When you do it step by step, it’s a pain, and time consuming, but not difficult.
What you’ll need
I’ve linked to the products we use, but most of these things come in multiple brands. This is just an example.
Garden Pump Pressure Sprayer. We’ve been using a ½ gallon sprayer from Harbor Freight. We don’t have a hose bib anywhere near our home but if you do, it looks like there are hose sprayer kits that could be easier to work with than this.
Protective Cleaning Bag. The one we have is no longer available, but it looks like this one. Make sure the one you get is big enough to fit over your minisplit.
A bucket to drain the cleaner into
A stepladder
Clean rags to wipe up overspray and clean the shrouds.
A flat head and Phillips screwdriver, to take the shroud apart
A clean sink and countertop to wash the “filters” (a word I use generously) and ideally, a laundry line to hang them on in the sun to sanitize them.
Some kind of a gentle scrub brush to wash the “filters”
Possibly a pressure washer if you want to use it gently and carefully to clean the plastic shroud. You could possibly even use it on very low pressure to clean the fins. I’ve done this with our trailer AC, but I haven’t tried it with our minisplit. Try at your own risk.
Some kind of cleaning product you tolerate. Lately we’ve been using Fantastik because it goes after the bacteria. It does have a scent to it but it doesn’t seem to linger beyond a few days. If you’re sensitive to smells, find something that works for you. You could use diluted Branch Basics or even dish soap.
How to do it
Slide out the filters. Take them apart and put them in a clean sink full of soap water. Let them soak while you’re working on the next steps.
Take the plastic covers off. You can get an expert out the first time to help you do this and/or check YouTube for your particular model. If you use a power drill, be careful not to overdrive it and split the plastic. As you take screws out, line them up on the counter in the order you removed them, to make it easier to put them back.
Carefully stretch the protective bag over the ends of the machine. The elastic makes this tricky and it’s paramount not to bend the fins if you can help it. Bent fins trap dirt, which can cause mold, and they also make the machine work less efficiently.
Optionally you can put the clear plastic cover over the front of the protective bag. We stopped doing this because we didn’t feel it was helping and it was getting in the way of accessing the fins.
Attach the hose to the protective bag and put the other end in the bucket.
Put a mixture of hot water and cleaning solution in your sprayer. Starting at the top, carefully spray the fins with solution. Make sure you get all of them, even the ones at the very back on top.
Optionally, at this point you can remove and clean the fan wheel. I wouldn’t suggest you attempt this the first time you’re cleaning the fins. It’s difficult. We did it once and didn’t feel that it was dirty enough to merit cleaning. We probably won’t do it again. Here’s a video with more information, should you decide you want to do it.
Most of the cleaning solution you spray into the machine will disappear down the condensate line. Some of it will run into the bucket. A little bit of water will run down the wall during this process. I have found no way around this. I try to mop it up before it hits the baseboard. You can have one person stand there with a rag while the other sprays the fins if you want to.
Once you’ve soaked all the fins with cleaning solution from every direction, let the fins soak while you go work on the other pieces.
Squeeze soapy water through the filters. Use your brush to scrub the large plastic filters. Rinse everything and hang in the sun to dry.
Using either a power washer on gentle, or a microfiber cloth, and some cleaning solution, clean out all of the pieces of the plastic shroud. Put those out in the sun to dry.
Use a clean fin tool to straighten out any bent fins. Possibly re-spray those fins with cleaning solution.
Refill the sprayer with plain hot water, and rinse all the fins.
Put the minisplit back together.
Run it on fan mode to dry it out.
Keeping it cleaner for longer
It’s best practice to always run your minisplit in cool mode on low, medium, or high fan mode, rather than auto. With auto, the fans turn off when the thermostat hits target temperature and the condenser shuts off. This means the fins sit wet. When the fan is always on, it dries out the fins between condenser runs.
Whenever you shut off cool mode, make sure you run it on fan mode for about half an hour to dry out the fins before you turn it off completely.
We finally installed a UV light when we cleaned the minisplit this time. We’d consulted with two companies and they were quoting us about a thousand dollars to install it and both strongly advised us not to do it. They said that UV light breaks down plastic, (true, it does, but the number of cleanings we’re having to do are also causing wear and tear) and that it won’t purify the air (true, it doesn’t, but we’re not expecting it to; we just want it to kill stuff on the fins.) We installed the Pioneer UV light that is no longer available for whatever reason. When we installed as directed, the UV lights were directly shining into the room. That is a hazard and can cause eye damage, so we took them out and re-installed them near the top where they shine on the fins but we can’t see them. Unfortunately it seems like the lights run all the time, not just when the minisplit is running, so we’ve been having to shut off the breaker to turn them off. Time will tell whether the UV light is useful or not.
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