During the summer months when the mechanically sweet smell of manufactured cold air is wafting through the house we often forget one important thing - air filters! Just like all living creatures on this planet, your central air conditioner needs to breathe too. It is a wise idea to check all removable filters that pull air through your house to be cooled in your , in most cases, attic and delivered back into the house. When filters start to have dust build-up there is a major issue brewing. The a/c unit must pull enough air through the system to remain healthy. I have written on this issue before but this time for a different reason. When excess build-up occurs the unit begins to over-work as it tries to get the temperature down resulting in longer run times, which equals higher electric costs and excess wear on the mechanical components that can lead to unit failure, which equals a very expensive repair or replacement. I know the latter part too well. When I bought my house the previous owner didn't bother to keep regular maintenance going and I had to buy a new central a/c when mine died during a hot spell, which if it's going to fail there is no time better than a hot spell when it's working the hardest.
Filters are cheap and new a/c's aren't! Keep enough filters on-hand or do like I did. I bought an electrostatic house filter. These filters work by 'charging' household particles, without electricity, in the air and capturing them onto the filter material. This is best described as a 'static electricity' capture, as the air moves across a metal mesh on the filter that sits on top of the filter material. They're available in several sizes and can also be obtained in a 'cut to size' type for odd sized intakes like mine. I found mine at Lowe's but it's not listed on the web site. Cleaning is a snap so long as you don't have a disposable filter. The original permanent electrostatic filters were metal and the newer generation are plastic, disposable ones are paper and should not be cleaned as described next. Permanent filters just need to be taken outside and the accumulated dust hosed off, let dry and reinstall like new. The permanent ones cost a little more but if you read my articles you will understand my thoughts on this, buy one time-use many times!
These filters can be found at your local building mega-stores like Lowe's and Home Depot. These links will take you to one size of one type of filter. Visit your local store for further sizes and options.

Also, do your car a favor and do the same for it! Your gas tank will thank you. (But that's another article).