As the summer season drags on, you might find that your window air conditioners are losing some of their cooling power. It could be that you installed them improperly, the effects of which are now being felt. Or a few key maintenance checks might be in order.

Our step-by-step video guide on how to maintain your air conditioner, based on Consumer Reports' testing of dozens of window air conditioners, will keep your home comfortable when the weather outside is anything but.

Step 1: Check the Placement

For starters, it's best to avoid placing a room air conditioner in a window that’s pounded by sun, since direct sun will force it to work harder. North-facing windows receive the least sunlight, or look for a window on another wall that's shaded by trees, an awning, or another source of coverage. Closing curtains and blinds is another way to reduce solar heat gain.

Moving indoors, it’s also important to keep heat-generating objects, such as a TV or floor lamp, away from the air conditioner. That’s because the unit's thermostat can sense their heat, causing the unit to run longer than necessary.

Finally, our tests have found that some room units do a better job blowing air either to the right or to the left. This won’t be a factor if the air conditioner is installed in a window located in the center of the room. But if the windows are all near a wall, choose one that will allow the air to blow toward the middle of the room, rather than into the wall. Some models are omnidirectional.

Step 2: Maintain the Machine

All room air conditioners have a filter behind the front grille that can get clogged with dirt and dust, which reduces airflow through the unit, diminishing its efficiency and ability to clean the air. A few times a season, pop off the grille and take out the filter. Remove debris with a vacuum then wash the filter in warm, soapy water. Let the filter dry before reinstalling it. If the filter is badly worn, it’s time for a new one.

You should also inspect the window seals around your unit to make sure hot air isn’t getting into the room or cold air escaping. If leaks are present, reseal around your unit with weatherstripping.

Step 3: Program It Properly

We’re seeing more programmable window air conditioners and even connected units that can be controlled from your smartphone. Whether you have one of these high-tech air conditioners or the manually operated kind, give some thought to the temperature setting. Recommendations from Energy Star are pretty strict: 78° F when you’re home, 85° F when you’re at work or away, and 82° F when you’re sleeping.

If that’s too hot to handle, see if you can at least tolerate slightly warmer temperatures, since you stand to save 3 percent on your air conditioning costs for every degree you raise the temperature.

Deep Discounts

Think you need to cut bait and spring for a new air conditioner? Mid- to late summer is a good time to find great deals as retailers look to unload the last of their inventories. It will probably be slim pickings, but you might get lucky and score a top pick from our air conditioner ratings for a fraction of its original cost.