The Midea U genuinely changed the window air conditioner world, providing quiet, efficient cooling without holding an entire window hostage for the summer. But in the first few years after its release, we began hearing from readers who had noticed mold growing on a fan visible inside the unit just behind the grille where the air flows out.

To be fair, this can happen with any air conditioner. “I’d venture to guess that upwards of 70 percent, maybe more of the AC units and mini-splits we encounter, if you took a flashlight and looked at the fan, you’d see mold,” Gabriel Erde-Cohen, CEO of We Clean Heat Pumps, told us. “Sometimes, the mold is just more apparent.”

We began reporting on this concern in summer 2023. We tried and failed to replicate a mold issue ourselves, and we disassembled our own Midea U in order to better understand its airflow and identify some problem points. We also reached out to Midea to ask about the issue. The company’s answer confirmed our findings: The fan, and thus any mold growth on it, is more visible in the U than it is in other ACs. Also, the problem can be more prevalent in rooms where people have installed oversize air conditioners, a practice that we discourage. We then wrote that the remedy, for many people with an appropriately sized AC, is to keep the fan running to dry out moisture and make sure the AC is tilted slightly backward to help with drainage.

Meanwhile, complaints to Midea persisted. At least two people filed formal complaints with the Consumer Product Safety Commission about the mold problem. (Many such complaints are posted publicly at SaferProducts.gov.)

We don’t know when Midea started looking into the issue, considering that it’s been evident for years, or why this particular action is happening now. But we did speak with Jonathan Midgett, PhD, the consumer ombudsman at the CPSC, who serves as a sort of public liaison for the agency’s internal processes. Although Midgett wasn’t familiar with this particular case, he did say that a two-year timeline would be reasonable for a company to investigate these sorts of complaints and develop a plan of action to address the problem. “Sometimes complaints do take years to get traction,” he explained. “You get one or two and just ignore it, then there’s three or four, and now it’s looking like there might be a pattern.”

Companies do have some responsibility for mold mitigation, according to the CPSC. “I know that it sounds like it’s not a mechanical failure, but it is a mechanical failure if there’s something wrong with the plastic or there’s not enough airflow to prevent mold growth,” Midgett told us, citing a 2013 mold-related recall of nearly one million Fisher-Price Rock ’n Play sleeper cribs.