As winter reluctantly leaves us and spring moves forward, it's time to consider air conditioner maintenance. Our air conditioners have been sitting idle, enduring the assaults of winter weather and the wear and tear of last season's use, not to mention the mice that have eaten the protective covering on the wires of your outdoor equipment. This all wreaks havock at the worst times.

The assaults of major snowstorms and arctic blasts have made our air conditioners the last things on our minds. In only a few weeks, if they are not working properly, they will be the first things on our minds.

When the season ended last summer, was your air conditioning in good working order? Have you needed repairs during the past two seasons? Is your air conditioner more than 10 years old? Does your energy bill increase dramatically when the weather gets hot?

These are all questions to ask yourself to help determine how your cooling system will perform during the summer heat that's about to arrive in Massachusetts.  Here are a few "repair or replace" tips:

If your air conditioner is 10 to 15 years old, it may still keep you cool, but it also may be costing you more than you know. New high-efficiency air conditioning systems can cut operating costs significantly. EnergyStar, a program of the federal government, says replacing an A/C that's more than 12 years old with a qualified model could cut your cooling costs by 30 percent.

An optimum HVAC system includes high-quality ductwork. Even the best heating and cooling equipment can't run at peak efficiency on its own: It needs a thoughtfully sized and designed and professionally installed system of ductwork to circulate warm or cool air throughout your home or business.

In the old days, home ducting was "designed" as a sometimes-convoluted mess. Often, installers ran ducts in longer sections than necessary in order to avoid pillars, beams, bearing walls and other structures. These days,  the best ductwork is designed with each individual home and its HVAC equipment in mind.

The size and capacity of your home comfort system are crucial factors in whether it can do its job properly. That's why it's wise to get a "load calculation" -- a measurement of the heating and cooling output your home needs.

A too-small system will not be able to keep up with demand, but it will work very hard trying -- leading to unnecessarily high utility bills. So should you just go out and buy the largest-capacity equipment to be safe? No. An oversize system is just as bad as an undersize system. You'll pay too much for the equipment and more complex installation. Beyond that, you'll get poor performance, as a too-big system will operate inefficiently and also increase your utility bills. Oversize furnaces can cause big temperature swings, while outsize A/C units fail to properly dehumidify your air because they don't run long enough.

Air conditioning systems over 10 years old are typically not very efficient; this is also the time when they require more repairs and maintenance. If your air conditioner is older, it may be time to consider upgrading your cooling system to a new, high-efficiency unit. When you do upgrade, you will have to decide which type of system to install: a split-system or a packaged unit.

So, what is the difference between these two types of air conditioning systems?

Winter nights in Massachusetts can be brutal. There's not much that's worse than coming home to a broken furnace and a freezing house.  Annual service for your heating and cooling systems helps to ensure this won't happen, and it also ensures your system functions most effectively and efficiently.

Installing energy-efficient appliances in your home can not only save money on your utility bills, it can save money on your federal taxes. Tax credits are available if you upgrade heaters, air conditioners and hot water heaters with equipment that meets energy-saving requirements.

To claim tax credits in 2011 you must:

Whether you invest in bonds or the stock market, you look for a payoff. That goes for major purchases as well. A high-miles-per-gallon vehicle will pay you back as you drive. Your heating and air equipment should be viewed no differently: An energy-efficient air conditioner can pay off, too.

With summer's arrival looming, now is the time to make sure your air conditioning system is equal to the task of keeping you cool when the weather heats up. Investing in preventive maintenance now can save you major headaches down the road, and it just might stave off a major failure when you're in the throes of a heat wave.