A homeowner who regularly cleaned their mini-split filters was surprised to discover buildup covering an internal fan after the cooling stopped keeping up.
The discovery came with a sizable maintenance quote of $620 to clean two units, with no guarantee that the service alone would restore performance.
Here's what to know
In a post on Reddit's r/hvacadvice community, the homeowner described having a pair of 18,000-BTU Mitsubishi H2i Hyper Heat systems installed four years ago.
Cleaning the mini-split filters was part of the homeowner's furnace filter replacement routine, which happened about every four months. The mini-splits had never operated without their filters installed.
While checking the unit recently, the homeowner saw a coating on the fan. The inspection followed trouble cooling the bedroom despite the regular filter maintenance. "So one day last week I opened the louvers while it was not running and found the fan was covered in... lint? Dust bunnies?" the original poster wrote.
The OP asked if cleaning could restore heating and cooling performance, and whether the quote was fair. The installer's cleaning price was $310 per unit for the air handler and compressor coils.
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More background
Heating was the main job for both systems; neither ran continuously.
Wildfire smoke or bedtime temperatures in the high 70s meant closing the windows for roughly four weeks of the year. Otherwise, overnight mountain temperatures dropped to about 50 degrees, allowing the homeowner to leave windows open.
A vent reading of 20 to 25 degrees below the surrounding temperature hadn't translated into adequate bedroom cooling. The room measured 440 square feet and had a 14-foot cathedral ceiling.
Commenters noted that cold air at the vent does not necessarily mean enough air is moving through the room.
One respondent, describing their company's cleaning process, explained that dirty coils and blowers can severely restrict airflow, even when homeowners regularly clean the removable filters.
What can be done?
The $310-per-unit quote drew support from commenters if the work included removing and cleaning the dirty components. Rather than assume that would solve the problem, they recommended evaluating performance after a thorough cleaning.
Outdoor cleaning of detached parts was central to the process one commenter described: the louvers, covers, blower, and drain pan were among the components removed. Their company charged $355 per indoor unit, including condenser-coil cleaning — $45 more per unit than the homeowner's quote.
Another commenter suggested buying cleaning equipment for about the cost of one professional cleaning and doing the work annually. However, that was a commenter's estimate, not a verified savings calculation or a manufacturer-specific maintenance schedule.
"If they actually pull and clean then yes reasonable pricing Will it fix issue? Maybe. Need to start there and then they need to see how it operates after. That amount of build up on the blower wheel definitely affects it," another person wrote.
Where can I learn more?
Other homeowners have faced similar questions about HVAC maintenance and service costs. These stories cover disputed diagnoses, filter upkeep, and outdoor-unit cleaning.
• A homeowner faced a $600 bleach treatment pitch before a local HVAC professional identified dust.
• A homeowner received a $13,000 AC replacement quote over a potentially much cheaper drain-clog fix.
• A Georgia HVAC professional said keeping the filter clean solves about half of summer AC problems.
• A homeowner skipped a 15-minute HVAC cleaning chore and discovered a badly clogged outdoor unit.
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