GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted
Best Practices

Minisplit Maintenance

Cleaning filters and coils is critical to effective operations and optimal performance

Dust buildup on ductless minisplit filters after at least 12 weeks

About a year ago at my home in Northern Michigan, it was noticeably chilly inside and around 35°F outside. The two single-zone, cold-climate minisplit systems should have had no problem maintaining the 70°F setpoint. I turned the systems off, popped open the covers, and sure enough the filters were caked with dust—it’d been a while since I last checked them. I removed the filters, cleaned them with a handheld vacuum, and reinstalled them. The system was back to normal.

Then, a few months ago, a friend shared an article about the annual maintenance costs of a minisplit system diminishing the savings after switching from natural gas. It’s difficult not to digress with counter arguments, but let’s focus on the annual maintenance. I learned that one important step includes a deep cleaning of the indoor unit, which was something I hadn’t done.

Then, I got to thinking about when I’ve helped troubleshoot minisplit systems. One of the first questions to ask is when the filter was last cleaned or changed. Responses have ranged from “regularly,” to “oh yeah, it’s been a while,” to “what filter?”.

Given a typical homeowner’s lack of awareness about the importance of filter maintenance and indoor coil cleaning, I figured it’s a good opportunity to share my experiences. I’ll start with basic operation and identify some components to better understand the importance of maintaining the systems. Then, I’ll move on to the procedures.

Rundown of the basics

Minisplit systems have at least two coils that are fin-tube heat exchangers, one for each indoor and outdoor unit. True to their name, they are made of a tube with multiple bends that has several fins welded to it. The fins are spaced roughly a millimeter apart, about the…

GBA Prime

This article is only available to GBA Prime Members

Sign up for a free trial and get instant access to this article as well as GBA’s complete library of premium articles and construction details.

Start Free Trial


  1. StephenSheehy | | #1

    We have our Fujitsu minisplits cleaned every two years by the company that installed them. A fair amount of gunk gets washed out. Costs around $500 total for three units. That price includes new filters.

  2. jonny_h | | #2

    This is honestly my biggest hang-up in my ongoing attempt to make a decision between ductless and ducted systems. The ductless is way easier to install, slightly more efficient, substantially lower cost, and nobody in my household cares about the "lump on a wall" appearance -- but the filters don't really provide much in the way of air quality improvement ("apple catechins" aside), need to be cleaned every 2-4 weeks(?!?), and still don't save you from needing to deep-clean the coils every year or two. I just want a ductless mini-split with an option for like MERV13 filters!

  3. HuntCountry | | #3

    This was very informative! Thank you for taking the time to share so much detail. We're getting close to pulling the trigger for a whole house (new construction) mini-split solution and the frequent filter cleaning has been a concern. Not the cleaning so much, but dragging a big ladder around the interior to access ceiling cassettes in 10 and 12 foot ceilings.

Log in or become a member to post a comment.



Recent Questions and Replies

  • |
  • |
  • |
  • |