Mini Split Maintenance: What You Can Do Yourself

Mini splits have a reputation for being maintenance free. They are not. They are just quiet about it until they are not, and by then you are usually calling me about a smell or a drip.

Here is the split between what you should be doing and what I should be doing.

Your job, and it is easy

Rinse the filters. Monthly in heavy use.

Pop the front cover on the indoor head. There are two mesh filters that slide out. Rinse them in the sink with lukewarm water, let them dry all the way, put them back. That is it. Five minutes.

People skip this because the units look clean from the outside. Pull a filter that has not been touched in a year and you will not skip it again. A loaded filter cuts airflow, which cuts capacity, which makes the system run longer to do the same work, which shows up on your bill.

Keep the outdoor unit clear.

Leaves and grass clippings in summer, snow and ice in winter. Give it a couple feet on all sides. In winter make sure it is not sitting in a drift and that meltwater is not refreezing under it and jacking it up off the pad.

Do not pressure wash the outdoor coil. The fins bend at almost nothing and once they are folded over the airflow is gone. Garden hose on low, from the inside out if you can get to it, or leave it for me.

Watch the condensate line in cooling season.

That is the small line running out of the wall under the head. It should drip outside when the unit is cooling. If you ever see water running down the wall under the indoor unit, shut it off and call. The drain is plugged and it will keep going.

My job

The blower wheel and the evaporator coil.

This is the one people do not know about. Behind the filters there is a barrel shaped blower wheel with a lot of narrow blades, and behind that the coil. Over a few years that assembly grows a film of dust, pollen, and in a lot of houses, mold. Filters do not catch it all.

That buildup is where the musty smell comes from when the unit kicks on. It also quietly kills capacity. You cannot reach it with a vacuum and a rag. Cleaning it properly means bagging the head, pulling the wheel in some cases, and washing the coil with the right cleaner. Every two to three years for most houses, more often if you have pets or run it hard.

Refrigerant charge and electrical.

Mini splits are a sealed system. If the charge is low, there is a leak, and topping it off without finding the leak is throwing money away. I check the charge, the line set connections, the disconnect, and the contactor.

Drain pan and pump.

If your head has a condensate pump, it has a float switch and a reservoir that both need cleaning. Pumps fail quietly and the first sign is water where it should not be.

What good maintenance actually buys you

Not much drama, which is the point. But specifically:

• Capacity you paid for. A dirty system does not put out what it is rated for, and you feel that on the coldest day.
• Lower running cost, because run time goes down when airflow goes up.
• No smell.
• Warranty standing. Most manufacturers require documented maintenance, and a denied claim on a compressor is not a small number.

Timing

Rinse filters monthly through heating and cooling season. Have somebody look at the whole system once a year, and plan on a deep blower and coil cleaning every couple of years.

If yours has been in five years and nobody has ever had the cover off past the filters, it is time. Call us and we will take a look.