The outdoor AC unit needs attention too — not just the indoor system (US)

Half of your air-conditioning system lives outside, on a concrete pad, quietly gathering cottonwood fluff, grass clippings, leaves and dust. The indoor half gets the filter changes; the outdoor condenser gets ignored until the bill climbs or the cooling fades. It's the same physics as fridge coils — a radiator can only dump heat if air can move through it — and the fix is equally cheap.

What the unit is trying to do

The outdoor unit doesn't make cold; it throws heat out of your home. The refrigerant carries the heat outside, the coil sheds it, and the fan pulls air through the fins to carry it away. When those aluminum fins are matted with debris, the heat has nowhere to go: the system runs longer for less cooling, the compressor runs hot — and the compressor is the part whose replacement costs enough that people replace the whole unit instead. ENERGY STAR's guidance treats this as basic monthly upkeep, alongside the indoor filter.

The monthly ten minutes, in season

Kill the power at the outdoor disconnect before you touch anything inside the unit. Clear leaves, grass and fluff from around and inside the top guard by hand. Gently rinse the coil fins from the inside out or top down with a garden hose — the debris should wash out the way it came in. Never use a pressure washer: the fins bend at the slightest provocation, and bent fins choke the same airflow you're restoring (a fin comb straightens minor damage). Then keep the machine's airspace: two feet of clear space all round, no mulch, no stored items, vegetation trimmed, and nothing stacked on top.

Season-by-season

Spring, before first run: rinse the coil, clear the pad, check the unit hasn't shifted out of level (a leaning condenser wears its compressor bearings), and remove any winter covers — don't run the unit with a cover on. Summer, monthly: the ten-minute clear-and-rinse, plus a glance at the insulated refrigerant line — insulation that's crumbling wants replacing, and there's where you stop and call, because everything beyond insulation is certified-person territory. Autumn and winter: clear leaves out of the top, and resist the full tarp wrap — a sealed cover traps moisture and invites rodents; a breathable top cover against falling icicles and leaves is the useful version. First run in spring: listen — grinding, screaming or buzzing mean call, not hope.

Sources: ENERGY STAR heating and cooling maintenance guidance (coil cleaning, clearance); manufacturer condenser-care conventions. Reviewed September 2026 · general information, not professional advice.