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What Type of AC System Do I Have?

Do you know what type of air conditioner is keeping you cool this summer? A little knowledge of air conditioning systems can go a long way towards maintaining your system and keeping it running at maximum efficiency for both comfort and energy savings.

Split System Air Conditioners

How air flows in and out of a split system air conditioning unit.

How they work - Ducting

In order for split system AC units to function, they have to have a delivery system for cool air. That delivery system is ducting. As the cooling process in the indoor evaporator coils takes place a blower or air handler blows across the coils to distribute cooling. The cool air enters ducts, channeling that air to every room in the home. So, unlike other air conditioners, split system AC units are able to cool an entire home with only one combined system. The cost of a split system is higher in comparison than other air conditioners but the cost difference is offset by the need for only one system to cool an entire home or building.


While split AC systems are expensive, they can allow an entire structure to be cooled. Other benefits to split AC units revolve around the ducts:

  • Properly installed ducts deliver cool air anywhere in the home, even to the room farthest away from the evaporator coil.
  • Well-circulated air pushes out stale air into the return ducts and removes contaminants to be trapped in the filter, keeping indoor air clean.
  • When ducting is located inside walls or other conditioned areas or is well-insulated, energy loss is minimized and a split system AC is an energy-efficient method of cooling.


Since split system AC units are so dependent on a balanced installation of ductwork, there can be disadvantages to these units as well:

  • Poor installation of ducts can lower the efficiency of your equipment. The shortest distance between your inside unit and the various rooms in the home is best. If ducting winds around objects, has sharp turns or is improperly sized, this slows down airflow speed, wastes energy and reduces comfort.
  • Metal ducting transfers heat and cold quickly. If the ducts are not inside conditioned spaces or properly insulated, there is a transfer of cooling into areas of the home where energy is wasted.
  • Filters must be maintained in split system AC units to ensure good airflow and proper comfort. Filters should be changed every three months or when dirty to prevent damage to the system and clogged air circulation.

Ductless Split Systems

A diagram showing hot and cold air flow into and out of a ductless split system for a home.

Ductless split air conditioning systems are comprised of an indoor unit mounted to the wall, and an outdoor component that sits next to your home. While ductless systems don’t use ducts, as their name implies, they do use hoses to run from the room(s) you want to cool to the outdoor condenser unit.

Window or Wall Units

A diagram of how a window air conditioning unit works and each part labled.

Window units house all the parts of an air conditioner – compressor, condenser, expansion valve, coil, and more – in one box that fits into the window of your home. Their installation is simple and they’re very portable. Wall units function similarly to window units, though their installation is not as simple since they require wall modification.

Benefits include:

  • Simple wiring allows the user to locate the unit near a home electrical outlet. They are compact and don't require a lot of space.
  • The primary maintenance is to keep the filter cleaned or replaced periodically.
  • Compared to other air conditioning equipment, they are low in cost.
  • They are self-contained and generally require few tools for installation.
  • Although they are commonplace items, window or wall units can have drawbacks as well as advantages, depending on what the buyer needs.


Because window or wall units are limited in size, they are generally limited in effectiveness as well. They are usually ineffective in cooling more than one room. Other limitations are:

  • Noisy when window mounted. These units can cause loose sashes to vibrate and the equipment itself can often vibrate and generate noise.
  • Require tight sealing whether wall or window installed. Air leakage around the unit reduces their effectiveness and drives up the cost to operate.
  • Because they are a single unit, window air conditioners invite easy ingress into unprotected homes by thieves if not properly installed.
  • Older units require more energy to run.
  • Multiple units are required for whole-house cooling.
  • Block views when installed in windows.

Evaporative Coolers

A diagram of an evaporative cooler showing its parts and how air flows.

The Concept

Evaporative cooling works best in dry climates by using the evaporation of water to draw heat out of the air. As a breeze or fan blows over a moist medium, such as fabric, the water molecules disperse into the air, absorbing the surrounding heat. If you come out of a pool or lake into the surrounding air on a hot day, as the water evaporates from your body, you feel cooled. It's the same concept.

The Drawbacks

Evaporation can take place only in climates with a low humidity because of the following issues:

  • Dry air is much more receptive to evaporation than humid air. These cooling units perform best in areas with low humidity which allows for quick evaporation.
  • A modern evaporative cooler is usually mounted on a roof or in a window. It operates with a fan blowing air across pads that are soaked with water and the pads must have a constant water supply to maintain their moisture.
  • The pads must be cleaned regularly or changed to remove thick, mineralized deposits since the water evaporates but leaves any minerals behind. The units must also be drained in winter to prevent damage to the equipment.
  • Since both humidity and temperature fluctuate, evaporative coolers work best on some days, poorly on others.

The Benefits

  • Air conditioning requires having a sealed home to maintain efficiency. Evaporative coolers are healthier because they use a constant flow of fresh air. The fan draws outside air in, and open windows or door, keep a breeze of healthy air flowing through the home.
  • They have a low environmental impact. The cost of using evaporative cooling is about one-third the cost of standard air conditioning.
  • Those concerned with healthy air for both the home and the planet have a solution for their needs with this type of cooling unit.

Package Air Conditioning Units

A package heating and air conditioning units with all of its parts labeled.

No Need For Ducts

These air conditioners are sold and installed as a single unit. The compressor is located on an outside wall or rooftop much like any other central air conditioning unit. Just inside the wall or ceiling space, the blower section and controls sit. Since the equipment is a package unit, there is no need for ducting. The refrigerant circulates the short distance from the outside compressor to the inside air handler and delivers cool air to the interior room instantly. There is no distance for cool air to travel, thus the units are very efficient in cooling quickly with little to no waste in efficiency.

Self-Contained Efficiency

Since they are a single unit designed for a confined space, their efficiency is unmatched for the job they are designed to perform. Package AC units are an inexpensive option for dorm rooms and other facilities giving the occupant full control over their environment. With no need for ducting and no requirement to cool a large multi-room area, package AC units are a smart way to bring cool comfort to such areas as:

  • Motel and hotel rooms
  • Campus dormitories
  • Single and double occupied nursing home rooms
  • Garage apartments
  • Guest houses
  • Small office spaces


While they are excellent for certain spaces, cooling a whole house room by room with package AC units can be costly. Large rooms or multiple room areas don't lend themselves to good air distribution with package cooling equipment. Cooling energy can become wasted in large, spacious areas. One end of the room can be quite comfortable while the farthest areas do not receive sufficient cooling. Package units can also be more noisy than other methods of air conditioning.

Locating your air conditioning system

To determine what kind of air conditioning system your home uses, the first step is to locate it. However, its location will vary based upon what type of cooling system it is. If you are inept at dealing with air conditioning systems, follow the “look but don’t touch” adage. No matter your level of experience, consult an expert for servicing your air conditioner, and during the checkup ask them to show you how to safely and properly care for it. Every year, numerous injuries are reported to the Consumer Product Safety Commission resulting from heating and air conditioning units including electrocution, lacerations, cuts, bruises, strains and sprains.

To learn how to better care for your air conditioner, including setting up a routine maintenance schedule, contact Aire Serv® Heating & Air Conditioning, Inc. Our expertly trained technicians have been servicing all models of air conditioning systems across the US and Canada since 1992.