Midea is voluntarily recalling about 1.7 million of its popular U and U+ Smart air conditioners because pooled water in the units may not drain fast enough, leading to mold growth.

The news comes as temperatures are rising across the U.S. and the official start of summer rapidly approaches.

The Midea air conditioners fit in windows and resonated with consumers because of their unique design, which allows consumers to close their window ‘through’ the unit.

The U.S. Consumer Product Safety Commission said that the recall also includes approximately 45,900 units sold in Canada.

The white air conditioners have brand names including Midea, Comfort Aire, Danby, Frigidaire, Insignia, Keystone, LBG Products, Mr. Cool, Perfect Aire and Sea Breeze. They were sold in three sizes of cooling power: 8,000, 10,000 and 12,000 BTU.