A Florida homeowner was told she needed two air-conditioning systems to keep her house cool. But when another technician investigated, they reported problems with the existing setup, including a restricted return airflow and an outdoor coil that apparently hadn't been cleaned in four years.

Here's what to know

The homeowner complained that indoor temperatures stayed at 74-75 degrees Fahrenheit or higher, even with outdoor readings in the mid-80s. In a Reddit post in r/HVAC, the technician identified the equipment as a 2022 4-ton system in Southwest Florida.

The technician estimated the system's lone 16-by-20-inch return grille could allow roughly 600 cubic feet per minute of airflow. The equipment itself was squeezed into an upstairs closet.

The service company's message to the homeowner was that the builder should have installed two systems. According to the technician, however, that company had serviced the existing system for four years without ever cleaning its coils.

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Commenters questioned some details in the post. "You showed us the indoor coil and it's clean as a whistle. Is the outdoor coil filthy?" one commenter asked.

The technician explained that the indoor-coil photo was included to show an absence of growth, not to illustrate dirt. "It was the condensing coil that was trashed," the technician clarified.

Despite the reported issues, the technician said the system hadn't shut down once.

What can be done?

Homeowners can ask whether a return grille suits the equipment before accepting a recommendation for a second air-conditioning system. They can also ask whether routine maintenance includes cleaning the outdoor coil.

In this case, the technician raised concerns about both the installation and ongoing service, not just the system size.

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"So to all ya'll slinging boxes, make sure the friggin application is suitable. If you're installers; if you see some s*** that ain't gonna fly, don't set the customer up for failure. Tell your boss or whoever else," the original poster concluded.

Where can I learn more?

Dirty AC coils and disputed repair recommendations have led other homeowners to question their service, too.

• A new homeowner investigating extreme energy use found years of buildup choking AC condensers.

• In Texas, a homeowner's 27-year-old air conditioner prompted a repair-or-replace decision.

• A homeowner who skipped a 15-minute HVAC chore found a supposedly new unit badly clogged.

• HVAC professionals urged a homeowner to question how refrigerant was measured after an AC diagnosis.

• HVAC technicians questioned a $6,000 coil repair quote, suggesting a possible R-410A upsell.

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