Spring tune-up checklist (before the first heatwave)

Connecticut weather skips spring half the time and goes from 50°F to 88°F in a week. You don't want to find out your AC has a problem on the day you need it. Here's the spring drill.

What you can do in 30 minutes

1. Replace the filter. Even if it doesn't look bad. Start the season fresh.
2. Clear vegetation around the outdoor unit. Two feet of clearance on all sides, four feet above. Trim the bushes. Pull the leaves out of the top grille. Sweep around the base.
3. Rinse the outdoor coil. Power off at the disconnect. Hose from the inside out at low pressure. Don't use a pressure washer.
4. Check the condensate line. Pour a cup of distilled white vinegar down the drain access tee inside, or a half-cup of bleach if you don't have anyone in the house with respiratory issues. Kills the algae before it clogs the line.
5. Test the system on a mild day. Set the thermostat 4°F below room temperature. The system should start within a minute, the outdoor unit should run smoothly, and within 10 minutes the supply registers should be 18–22°F cooler than the return air. If they're not, you have a problem to solve before July.

What we do on a tune-up visit (and why)

• Check refrigerant charge with gauges. A system that's even 10% low on charge runs longer, costs more to operate, and shortens compressor life. We can't tell by looking — it requires gauges and the right ambient conditions.
• Test capacitors and contactors. Capacitors degrade with age and heat; we replace them at 80% of rated value, well before they fail in the middle of a heat wave.
• Inspect electrical connections. Tighten lugs at the disconnect and the contactor. Loose connections cause a cascade of weird intermittent failures.
• Clean the outdoor coil professionally. A real coil cleaner with a soft brush gets out the embedded dirt your hose can't reach.
• Verify temperature split, static pressure, and amp draw. Three numbers that tell us whether the system is operating in spec. We document these — a year later we can see exactly what changed.