Straight answers.

SEER stands for Seasonal Energy Efficiency Ratio. It compares how much cooling an air conditioner delivers over a typical cooling season with the electricity it uses: the higher the rating, the more efficient the system. Newer equipment is rated under an updated version of the standard, SEER2, which tests in conditions closer to real use. The right rating for a replacement depends on the space, how much the system runs, and the budget, and the estimate covers it.

Good maintenance combines a few simple habits with regular professional service:

• Check the air filter regularly and replace or clean it when it looks dirty.
• Keep the outdoor unit clear of plants, leaves, and debris so air can move around it.
• Keep supply vents and return grilles open and unblocked.
• Schedule a professional visit to check the coils, the condensate drain, the electrical parts, and how well the system cools.

Some water is normal. As warm, humid air passes over the cold indoor coil, moisture condenses and is carried away by the condensate drain line; that is how the system dries the air. Water where it should not be, such as around the indoor unit, on a ceiling, or overflowing the drain pan, usually points to a clogged drain, a loose line, or a coil that is freezing up. If you see that, turn the system off and have it checked.

There is no single age, but replacement is worth considering when several of these add up:

• The system is more than about 10 years old and needs repairs more often.
• A major repair would cost a large part of what a new system costs.
• Some rooms never get comfortable, or the space stays humid.
• Electric bills keep rising without a change in how you use the system.
• It uses an older refrigerant that has been phased out, which makes repairs harder.

Partly. Changing or cleaning the filter, keeping the outdoor unit clear, and making sure vents are not blocked are simple tasks you can handle. Checking refrigerant, cleaning coils, properly clearing the drain, and testing electrical parts take training and tools, and handling refrigerant requires certification. Those are best left to a technician.

Regular maintenance helps the system:

• Use electricity more efficiently, because clean filters and coils let it work less.
• Last longer, with less wear on the compressor and other major parts.
• Avoid breakdowns on the hottest days, when service is busiest.
• Keep the air cleaner and the drain clear, which matters in Florida humidity.

Before the season of heaviest use. In South Florida that usually means late winter or spring, before the summer heat sets in. Because systems here run most of the year, a second visit during the year can make sense, especially for equipment that runs constantly or serves a business.

Ask for a check if you notice any of these:

• Little or no cold air.
• Weak airflow from the vents.
• Unusual noises, such as rattling, banging, or buzzing.
• Musty or burning smells.
• Water leaking around the indoor unit.
• The system takes a long time to reach the thermostat setting, or runs almost nonstop.
• Electric bills rising for no clear reason.

It depends on the equipment, how it was installed, how hard it works, and how well it is maintained. As general guidance, many central systems last around 10 to 15 years. In South Florida, where systems run most of the year and salt air can wear outdoor units faster, regular maintenance makes a real difference.

Weak cooling usually has a cause a technician can find. First make sure the thermostat is set to cool and the filter is clean. Other common causes:

• A dirty or clogged filter that restricts airflow.
• Dirty indoor or outdoor coils that cannot move heat well.
• Low refrigerant, usually because of a leak.
• A failing compressor, fan motor, or capacitor.
• Thermostat or electrical problems.
• A system that is too small for the space.
• Blocked vents or return grilles.