Mini splits — also called ductless heat pumps — are one of the most efficient and versatile HVAC options out there. They’re quiet, energy-saving, and perfect for older Massachusetts homes that don’t have ductwork. They are a “closed loop” inverter system so they are hyper efficient!

But just because they’re low-maintenance doesn’t mean they’re no-maintenance. And we’ve seen a lot of Massachusetts homeowners in towns like Framingham and Waltham run into problems that could’ve been easily avoided with a little know-how.

So if you have a mini split — or you’re thinking about installing one — here are 5 common mistakes to avoid (and what to do instead).

1. Using the Wrong Mode or Fan Setting

Mini splits come with multiple modes: Cool, Heat, Dry, Fan, and Auto. But “Auto” doesn’t always do what you think it does. In fact, it can cause the system to switch between heating and cooling unexpectedly — especially during Massachusetts’ shoulder seasons.

We often hear:

“Why is it blowing warm air in the summer?”
“Why does it turn off and on all the time?”

In many cases, it’s simply a mode setting issue. To avoid surprises, we recommend setting your unit to Cool in the summer and Heat in the winter, rather than leaving it on Auto year-round.

2. Never Cleaning the Filters

This one’s big. Mini split filters should be cleaned every 4–6 weeks during peak use — especially if you have pets, pollen, or live near construction or trees.

A clogged filter reduces airflow, forces your system to work harder, and can even cause the unit to stop cooling entirely. We’ve responded to plenty of “no AC” calls where the only fix needed was a quick filter rinse.

To clean it, open the front panel, remove the mesh filter, rinse it under warm water, let it fully dry, and reinstall it. That’s it — 5 minutes of work can save you a service call.

3. Shutting the System On and Off Too Often

Unlike older HVAC systems, mini splits are designed to run continuously at low speeds. Turning the system on and off constantly can actually reduce efficiency and wear out components faster.

Instead of powering your unit down every night or while you’re at work, set the temperature slightly higher when you’re away — or use a programmable controller or smart thermostat if you want automation.

This allows the system to maintain a steady indoor climate without wasting energy on big temperature swings.

4. Skipping Annual Maintenance

We get it — after all you probably heard the phrase “set it and forget it!” Mini splits seem so hands-off that regular maintenance might not feel necessary. But just like a car, they still need annual attention to perform their best.

Even if you clean the filters, a tune-up helps prevent:

  • Refrigerant leaks

  • Drain line clogs

  • Dirty coils

  • Electrical wear

  • Efficiency loss

Endless Energy’s mini split tune-up includes all of the above — and helps you avoid emergency breakdowns during a heat wave or cold snap.

5. Installing the Wrong Size (or Using One Unit for Too Many Rooms)

One of the biggest mistakes we see isn’t made by homeowners — it’s made by installers. A mini split that’s too small for your space won’t keep up on hot or cold days. One that’s too large can short cycle and lead to poor humidity control and early wear. A smart installer will also understand that the turndown rate with heat pump brands like Mitsubishi is a critical factor to consider when designing a system.

Similarly, trying to cool your entire home with one wall-mounted unit in the living room usually leads to frustration. That’s why we design custom multi-zone systems with the right number of heads — and the right capacity — for your layout.

Bonus Tip: Installing the Wrong Size (or Using One Unit for Too Many Rooms)

After your mini-split system has finished cooling a room and you want to stop using it – don’t just turn it off! It’s generally recommended to keep the fan running in “Auto” or a low fan speed setting, rather than turning it off completely. This helps to circulate air, maintain a consistent temperature, and potentially prevent condensation buildup, especially in high-humidity environments…keep that potential mold away!

Want to Get the Most Out of Your Mini Split?

Avoiding these five mistakes can help you:

  • Improve comfort

  • Extend your system’s lifespan

  • Lower your utility bills

  • Prevent surprise repairs

Whether you already have a system or you’re just exploring ductless cooling and heating for the first time, Endless Energy is here to help you do it right. If you’d like to schedule a mini split repair or mini split maintance give us a call at 508-501-9990 or you can schedule directly online.