Late summer heat can be sneaky. Just when you think cooler evenings are around the corner, the thermostat creeps back up, and your air conditioner has to rally for another stretch. The end of the season can be hard on an HVAC system that’s already had a long summer. At One Hour Heating & Air Conditioning® in Fullerton, CA, we help homeowners get the most out of their cooling equipment by having one of our technicians take a look. If your AC has felt sluggish lately, now’s the time to prep and schedule an Air conditioning tune up before temperatures spike again.

Why Late-Summer Heat Puts Extra Stress on Your System

By August or early September, your AC unit has already worked through weeks of long cycles, hot afternoons, and even occasional humid days. That constant demand doesn’t leave much time for recovery. If the system’s been straining to keep up or running longer than usual, the last heatwave can push it past its limits. Late-summer heat can also feel different inside your home. The sun hangs lower, so it hits windows at new angles. Attics stay warm well into the evening. If your home didn’t stay cool in July, it’s not going to get any easier now. You may notice the house takes longer to cool off or the thermostat isn’t quite reaching the set temperature.

Why You Should Check the Outdoor Unit Before the Heat Returns

When your air conditioner runs for weeks at a time, the outdoor unit takes a beating. Leaves, dirt, grass clippings, and dust can accumulate around the coils or be pulled through the fins of the condenser unit. That buildup blocks airflow and makes it harder for the system to release heat, which slows down cooling inside your home. Late summer is a good time to give that unit a quick visual check like you did in spring. Walk around it and look for anything stuck to the fins or collecting inside the base. If there’s significant debris inside or on the coils, it’s best to call for an HVAC tune-up to ensure safe cleaning. Trim back plants or shrubs that are growing too close to the unit. If you see a light layer of dust, you can gently rinse it off with a low-pressure hose — but avoid blasting the fins with high pressure, which can cause damage.

How Often Should You Change Your Filter?

Your air filter plays a bigger role than most people realize. It keeps dust, pollen, and debris out of your HVAC system. If it’s clogged, airflow drops quickly. That means your AC has to work harder to push cool air through the vents. It might run longer, shut off early, or struggle to cool certain rooms. If you hold the filter up to the light and can’t see through it clearly, it’s time to replace it. This small task helps protect the system, improve airflow, and keep energy bills in check. It also helps keep the air in your home cleaner, so dust and other particles don’t get recirculated. As a general rule, replace your filter every 30–60 days for larger households or homes with pets, and up to every 90 days for smaller households without indoor air quality concerns.

Can Duct Cleaning and Sealing Help With Cooling?

Air moves through a network of ducts before it ever hits your vents. If those ducts are dirty, leaky, or blocked, your cooling system loses performance. Gaps or loose joints let cool air escape into the attic or crawl space instead of the living areas. Dust and debris inside the ducts can also slow down airflow and push allergens back into the rooms — although duct cleaning should be done mainly when there’s visible mold, pests, or significant buildup. Late summer is a great time to seal leaks in your ducts. You’ll get better airflow, and your AC won’t have to run as long to cool the space. If you’ve noticed one room always stays warmer or the air feels weak coming from certain vents, duct issues could be part of the problem. Sealing leaks keeps the system tight. That means less wasted energy and more consistent temperatures from room to room. Targeted repairs and a thorough cleaning (when needed) can make a noticeable difference during those last waves of heat.

Should I Be Checking for Air Leaks Around the House?

Even the best AC system can’t keep up if cool air is leaking out of your house. Doors, windows, attic hatches, and even outlet covers can let air slip out, allowing warm air to sneak in. On hot days, this causes the system to cycle more frequently just to keep up. You end up using more energy for less comfort. Late summer is the perfect time to check for leaks. Walk around the house and feel for drafts near windows and doors. Use weather stripping, caulk, or foam sealant to close up the worst spots. If you’ve never had an energy audit, it might be worth scheduling one to pinpoint where air losses are happening.

Can Attic Insulation Help My AC Run Better?

Attic insulation keeps heat from building up in your living space. Without it, the sun beats down on the roof and turns your attic into an oven. That heat seeping into upstairs rooms forces your AC to run longer and work harder to pull temperatures down. If your attic feels hot late into the night, or if upstairs rooms stay several degrees warmer than the rest of the house, insulation could be the issue. Adding or topping off insulation helps slow that heat transfer and gives your HVAC system a break.

Get Your AC in Perfect Condition Today

Summer heat doesn’t stick to a schedule, and your AC still has work to do before fall finally settles in. A little prep now can save you from mid-season repairs and help your system finish strong. We also offer AC tune-ups, duct repairs, and thermostat upgrades to help you get the best performance out of your HVAC system when the heat hits hardest. If you’re not sure where to start, book a late-summer tune-up with One Hour Heating & Air Conditioning® and stay ahead of the heat.

FAQs

Homeowners sometimes aren’t sure how to keep their homes cool during the late summer. Here are some common questions and our advice.

How often should I change my filter?

In the summer, especially during prolonged periods of heat, filters can become dirty more quickly. If you’ve been running the system daily, checking the filter monthly is a great habit to have. Most homes can go 30–90 days between changes, but pets, allergies, or nearby construction can shorten that window.

Is late summer harder on my AC?

Yes, late-summer heat can be hard on your AC. The extra strain can cause parts to fail, such as motors overheating, capacitors wearing out, or coils losing efficiency. Prepping your system now helps you avoid last-minute breakdowns when demand is still high and appointment slots are limited.

Can attic insulation help with cooling?

Yes, attic insulation helps with cooling your home. You don’t need to remove everything. Sometimes, topping off existing insulation or sealing a few gaps around pipes and vents can make a big difference.