After the cotton falls: when to clean the coil

The canal’s trees, counted

In 2016 the High Line Canal Conservancy had every tree along the canal wider than six inches inventoried: 23,677 trees of 97 species.

That densest stretch is in South Suburban Parks and Recreation District and the City of Cherry Hills Village: the canal runs through this village at its most heavily wooded.

What the cotton does to a condenser

Cottonwood trees are either male or female. CSU Extension explains that female flowers are pollinated in April, and their seed capsules split open in June to release seeds on wind-borne cotton. With doors and windows open, that fluff reaches the kitchen. A built-in pulls room air through its grille and across the condenser, and the cotton mats on the face of the coil on top of the dust already there. Less air through the coil means longer running, a hotter compressor and a fresh-food side that drifts up just as the heat arrives.

So: clean after, not before

A coil cleaned in May is bare for June’s cotton. Clean it once the cotton has stopped, usually late June or early July, and look again before the hottest weeks. Sub-Zero’s own spacing is six to twelve months between cleanings, closer together in homes with pets; near the canal, make this one of them.

Signs the coil is already matted

• The grille face looks fuzzy or grey from a step away.
• The compressor runs far longer than it used to on warm afternoons.
• The fresh-food side reads above 38°F with nothing else changed.
• On models that display one, a message asking for the condenser to be vacuumed.