Even if your air conditioning unit is still working, depending on the type of system in your home today, you could recoup your investment in a new system in as little as three years. However, that doesn't mean that your system needs to be replaced. Furnaces, air conditioners, and other heating and cooling systems have made tremendous gains in efficiency over the past five years, so if you have an older unit, it is worth taking a look at whether or not a repair is the best investment.
To clean your air conditioner drain, first shut off the power to your unit at both the thermostat and the breaker. Then remove the drain pan. If the pan is full of water, soak up the liquid with a few towels or rags or use a wet vacuum. You can use a solution of water and distilled vinegar, or substitute peroxide for the vinegar, to clean out the drain pipe. Let the pipe sit for a while in the solution and then put all the parts back in place. Once you start using your air conditioner on a regular basis, check it periodically to ensure condensation isn't building up.
In hot weather, air conditioning can prevent heat stroke, dehydration from excessive sweating and other problems related to hyperthermia. Heat waves are the most lethal type of weather phenomenon in developed countries. Air conditioning (including filtration, humidification, cooling and disinfection) can be used to provide a clean, safe, hypoallergenic atmosphere in hospital operating rooms and other environments where proper atmosphere is critical to patient safety and well-being. It is sometimes recommended for home use by people with allergies.