As temperatures climb with the season’s first heat wave, your air conditioner is asked to do more work than it will on milder days. A little preparation now can help prevent common problems—like poor airflow, frozen coils, or system shutdowns—when demand spikes.

Start with the simplest win: check and replace the air filter. A clogged filter can restrict airflow, make the system less efficient, and cause the indoor coil to overcool and freeze. If the filter looks dirty or has been in place for more than about one to three months (depending on usage and indoor air quality), replace it with the correct size and rating.

Next, clear the outdoor unit and protect airflow. Make sure the area around the condenser is free of leaves, grass clippings, and debris. Trim back plants or brush so air can move in and out freely. Also remove any items stored nearby that could block vents during windy or stormy weather.

Check for airflow problems and visible warning signs

If your AC struggles to cool even before the heat wave hits, look for practical indicators. Make sure the indoor supply vents are not blocked by furniture, curtains, or rugs. Listen for unusual rattling or grinding sounds, and pay attention to musty or burning odors—both are reasons to pause and contact a professional.

During this first round of checks, also verify that the thermostat is set correctly. Ensure you’re using the proper mode (usually “cool”), the fan setting is appropriate, and schedules aren’t fighting your daily routine. For homes that have programmable thermostats, confirm the temperature targets for peak hours are reasonable to avoid constant cycling.

Test the system before you really need it

Try running your AC for a short period when it’s warm outside, not just during moderate conditions. This gives you a chance to spot obvious issues—like weak airflow from the vents, ice buildup on the indoor unit, or frequent cycling—before the hottest day of the season forces the system to run continuously.

Clean around the indoor unit if it’s safe to do so. Dust and debris can collect on grilles and surfaces, affecting airflow and indoor air quality. If you’re unsure how to access parts without risking damage, stick to visible cleaning and leave internal service to a licensed technician.

Consider professional maintenance—especially if reliability matters

For many households, the fastest route to confidence is scheduling seasonal maintenance before peak temperatures. A technician can inspect refrigerant lines, check electrical connections, measure airflow, and look for early wear on components. This is particularly important if your system is older, has had repairs in the past, or you’ve noticed performance changes over the last few weeks.

Finally, once the heat wave begins, aim for steady comfort rather than aggressive temperature swings. Keeping doors closed, using fans strategically, and shading sunny rooms can reduce the load on your AC. If the unit doesn’t cool as expected or trips a breaker, stop troubleshooting beyond basic filter and clearance checks and seek service.

By addressing airflow, cleanliness, and basic system readiness now, you can help your air conditioner perform more reliably throughout the first—and most demanding—days of the season.