Now that we’re into some of the hottest days of the summer those of you with central air conditioners might be finding that on the really hot days your home isn’t staying as cool as it once did. Maybe you’re even finding that your central AC isn’t able to keep up with a stretch of high heat and humidity that lasts several days or more. Here are some quick things I’ve learned that you can do to improve the efficiency and cooling ability of your central air conditioner:

The previous owners of my home severely cut down their central air conditioner’s cooling ability by putting makeshift scented filters in all the air vents.

First, you’ll want to make sure that you’re regularly maintaining your central air conditioner properly by changing the filters regularly, cleaning out the outside compressor unit and generally taking good care of it even when it’s working just fine. There are lots of different brands and designs of central air conditioners now, but they all require the same basic care: keep them clean and clear and they should keep you cool.

Next, you’ll want to be sure your AC is working well. If it isn’t working at all or if it is only providing very little cool air then you may want to try using some basic central air conditioner troubleshooting techniques just to get it running. Simple things like fuses, switches and batteries can often be overlooked when you’re hot and miserable and afraid of spending a day or night in scorching heat.

If your central AC is indeed working but just not keeping things as cool as you’d like, then it’s time to start trying to make the system more efficient. One of the best places to start is with the metal ductwork that brings the cool air to various rooms. You’ll want to first check for leaks or obvious holes or breaks anywhere along the ductwork. Some homes have ductwork that is easily accessible in a basement, while others have ductwork that is strung through attics or in crawlspaces. There are a few ways to look for leaks, but a visual inspection is always best. Get your flashlight, put on some gloves and just look up and down all the trunks and arms of your metal ducts, looking for any sort of breakages, cracks or even pinholes that may have developed. Sometimes you can find hole just by standing still and listening for a slight hissing of air when your AC is running.

To repair little holes, breaks and other small leaks you should not use “duct tape” but rather use the silvery foil tape designed for sealing metal duct work. It’s thick and sticky and it’s essentially the equivalent of sealing up holes with thick aluminum foil. A little goes a long way and it’s a heck of a lot cheaper and easier than trying to replace an entire piece of metal duct work. Even a little pinhole can be responsible for a huge loss of air (think about how a tiny hole in your tire can drain it in minutes) so be sure to make your ducts as air tight as possible.

Foil tape designed for HVAC repair can seal up most small leaks and cracks in metal air ducts easily.

Next, you’ll want to go around your house and inspect all the vents to make sure nothing is blocking the air flow of your central air conditioner. You’d be shocked at some of the things that make it into those ducts, from animal nests (eww!), to toys to dry sheets and more. You can generally get an idea if a duct is blocked or not by comparing the airflow coming out of it to all the others. If very little air is coming out compared to the other vents near it, then you might have a blockage. You can usually take off the vent cover and try to see what’s in there (use a flashlight and a mirror) or you can poke around with a plumbing snake or some sort of flexible stick or tube.

Finally, if your home is still unable to stay cool during hot spots you may want to think about insulation. You can consider adding more insulation to your attic and walls, you can consider getting more energy efficient windows and doors and you can even install insulation around your home’s metal ducts. Insulation won’t improve how your air conditioner runs, but it will help improve how long the cool air will stay inside your home before warming up again.

When all else fails, you may want to consider contacting an HVAC professional or environmental energy to run a home energy audit. Good luck and try to stay cool this summer!