Please check and make sure that Is it making strange noises? Is it cooling or heating all areas of your home sufficiently? Has it been taking longer to cool down or heat up? Have your utility bills been rising for no apparent reason? Any of these are signs that you may have a problem that needs service. In most cases, the longer you delay, the worse any underlying problems will get. So be sure to contact Horizon Services to check out your system whenever you notice anything out of the ordinary.