Central air conditioning systems have a maximum useful service life of about 15 years. That’s really the drop-dead time, when you must replace rather than repair. Before you reach that point, however, stuff happens: wear and tear, minor component failure, and out-of-spec adjustments. Most malfunctions are routine and, even better, some are preventable. Here are four problems that could put you out of air conditioning, just when you need it most:

You know that little breeze that sneaks in around the window in the dining room? And the draft you feel as you pass electrical outlets in the living room? Most homes have areas of air infiltration like these, where unwanted outdoor air gets in and conditioned air flows directly out, with energy wasted in each direction.

Chances are, if you’re like most residents here in the Minneapolis metro area, you end up running your air conditioner constantly during part of our humid summers. Every year, a certain number of unlucky homeowners end up with water or moisture damage in their homes, even to the point of a ceiling collapse. That’s because air conditioning systems produce more condensation than you’d think and can do quite a bit of damage before the often hidden mold and rotten wood are discovered.

With cooling being the largest energy expense in most homes during the summer, energy bills can take a major jump during the hottest parts of the year. If you’d like to start spending less on cooling your home, one way you can do this is by reducing your cooling load.

One simple way to enhance the air quality in your home is to choose HVAC filters with higher MERV ratings. Filters for cooling and heating appliances normally are assigned a MERV, or Minimum Efficiency Reporting Value. The numbers range from 1 to 16 for residential systems, and the higher the number, the smaller the particles the filter will capture before your home’s air enters the A/C or furnace.

If you are planning repairs or upgrades to your HVAC system, do your research and hire the best possible contractor for the job. Here are some things to consider when hiring an HVAC contractor:

If you’re reading this article, you may have quite a bit to gain by upgrading to high-efficiency air conditioning in your Twin Cities area home. After all, you’re online researching these units for some reason, and the most likely is that you aren’t happy with your current cooling equipment.

These days it seems like the Internet touches every aspect of our lives in some way, including home thermostats. The latest models of smart thermostats utilize Internet interfacing and computerized technology to give you control of home comfort, energy efficiency and all compatible home-comfort systems at the touch of a smartphone app or the click of a mouse.

It’s easy to take your home’s ductwork for granted—after all, it’s out of sight and seems to do a good job delivering heat and air conditioning to your rooms. But did you know that a typical house loses about 20 percent of its conditioned air before it ever gets delivered? Many homes’ ductwork has holes, bad connection points, or other spots where air leaks out. Don’t pay money to heat and cool your attic. Have your ducts sealed and enjoy long-term reductions in your utility bills.

It can be difficult to decide whether repairing or replacing your air conditioner is the best move for your home. Here are some signs that it’s time to stop paying the repairman and invest in a new, more efficient system for your home this summer: