Get your cooling system ready in March or early April, before the first hot week: change the filter, clear and rinse the outdoor unit, flush the condensate drain, check the thermostat and its schedule, run the system for 20 minutes on a mild day and check for cold air and no ice, and book the spring tune-up while contractors still have openings. Fifteen minutes now prevents the two most common June calls: a frozen coil from a dirty filter and a flooded pan from a clogged drain.
The checklist
- Filter. Replace it, and note the size and date. Filter guide.
- Outdoor unit. Power off at the disconnect. Clear leaves, grass and pollen from the coil and two feet around it; gently rinse the coil from inside out with a hose (no pressure washer). Check the unit is level and the pad hasn’t sunk. Restore power.
- Condensate drain. Find the drain access near the air handler and pour a cup of distilled vinegar down; check the pan is dry and the float switch (if any) moves freely. If the drain runs to the outside, make sure the outlet isn’t blocked.
- Vents and returns. Open and unblocked; vacuum grilles.
- Thermostat. Fresh batteries; mode to Cool; check the schedule (and, for heat pumps, that any winter aux settings aren’t costing you now); fan on Auto.
- Test run. On a day above 65°F, run cooling for 20 minutes. Air at the vents should be 15–20°F cooler than the return; the outdoor fan should spin quietly; no ice on the lines after 30 minutes. If anything’s off, AC not cooling.
- Book the tune-up. What it should include.
North Carolina notes
Pollen: March–May coats outdoor coils yellow; rinse mid-season too. Coast: rinse monthly against salt. Crawlspace air handlers: check for standing water and duct sag while you’re down there. Every contractor on the North Carolina registry shows the license status we found.