Air Conditioner vs Air Handler: The Differences


Air conditioners and air handlers are both integral components of HVAC (Heating, Ventilation, and Air Conditioning) systems, but they serve distinct functions within the system. Here’s a summary of the key differences between air conditioners and air handlers:

1. Function

  • Air Conditioner: An air conditioner is responsible for cooling the air. It removes heat from indoor air, releases it outside, and circulates the cooled air throughout your living spaces.
  • Air Handler: An air handler’s primary function is to circulate conditioned air. It may not have a cooling or heating function on its own but works in conjunction with other components (such as a heat pump or furnace) to distribute treated air throughout the home.

2. Components

  • Air Conditioner: An air conditioner consists of components like a compressor, condenser coil, evaporator coil, and refrigerant. It operates independently to provide cooling.
  • Air Handler: An air handler contains a blower fan, an evaporator coil, and a filter. It relies on other HVAC components for heating or cooling functions.

3. Cooling Capacity

  • Air Conditioner: Designed primarily for cooling, air conditioners are efficient at lowering indoor temperatures during hot weather.
  • Air Handler: The air handler’s primary role is to distribute conditioned air; it doesn’t provide cooling capacity on its own.

4. Heating Capability

  • Air Conditioner: While air conditioners cool indoor air, they can’t provide heating unless they are part of a heat pump system.
  • Air Handler: Air handlers can be part of both cooling and heating systems. When paired with a heat pump or furnace, they distribute both heated and cooled air.

5. Installation Location

  • Air Conditioner: Typically installed outdoors, air conditioners are responsible for the exchange of heat with the outdoor environment.
  • Air Handler: Air handlers are usually installed indoors, often in attics, closets, basements, or utility rooms, and are connected to the ductwork.

6. Air Quality

  • Air Conditioner: While air conditioners filter some particles from the air, their primary function is temperature control. They may not offer advanced air purification features.
  • Air Handler: Air handlers are often equipped with air filters that can help improve indoor air quality by capturing dust, allergens, and pollutants as air passes through.

7. System Efficiency

  • Air Conditioner: Air conditioners are essential for cooling, and their efficiency is measured by their SEER (Seasonal Energy Efficiency Ratio) rating.
  • Air Handler: The efficiency of an HVAC system, which includes an air handler, depends on the overall system’s performance, including the heat source (e.g., heat pump, furnace) and the thermostat’s control.

Air Handler vs Air Conditioner

To understand how different air handlers are from air conditioners, you must first understand how they work.

How an Air Conditioner Works

When comparing air conditioners and air handlers, most of us actually refer specifically to central air conditioners. But as you already know, there are other types of air conditioners like mini-splits, window and portable air conditioners.

Air conditioners have an outside unit and an inside unit. The outside unit houses the compressor and the condenser coil while the inside unit houses the evaporator coil.

The 3 main components are connected together using copper pipes. Evaporator and condenser coils are both heat exchangers.

Inside the evaporator coil, heat from indoor air is absorbed while inside the condenser coil, the heat is released to the surrounding air. The heat exchange is effected by a chemical known as a refrigerant.

The refrigerant enters evaporator coil inside the house as a very cold liquid. Depending on whether the AC is connected to an air handler or furnace, the fan will pull hot air from the house and move it across the coil.

The refrigerant will absorb heat from the indoor air and therefore cool it. Cooled air is then supply back to the house using the supply air ducts.

After absorbing heat from the air, the refrigerant will vaporize, leave the evaporator and enter the compressor.

Inside the compressor, the pressure of the refrigerant gas will be increased, a process that also dramatically increases its temperature. It is important for the refrigerant temperature to be increased so that heat can be transferred to the outside hot air.

Remember: In heat exchange, heat is transferred from a point of high concentration to a point of low concentration.

From the compressor, the superheated refrigerant enters the condenser coil. As it moves through the coil, the condenser fan blows cooler air over the coil which absorbs heats from the refrigerant and dissipates it to the outside air.

By the time the refrigerant is exiting the condenser coil it will have lost so much heat that it will have condensed back to a liquid and ready to go back to the evaporator coil for more cooling.

As you can see, the function of a condenser is very similar to that of the air handler but they are quite different.

A condenser is found outside the house while the air handler is located inside the house. Secondly, a condenser is a heat exchanger (removes heat from the refrigerant) and releases outside while an air handler merely moves air from the house to the cooling/heating coils and back to the house.

How an Air Handler Works


As I have mentioned, an air handler works with either an air conditioner or heat pump. Its most important part is the blower and that is why some folks also call it a blower.

However, a complete air handler consists of a blower, evaporator coil, electric heating strips, and air filter among other smaller parts. It is a metallic box which looks like a furnace and installed somewhere in the attic, basement or closet.

Air handlers are connected to the return and supply air ducts. Return air ducts are the ducts that bring hot or cold air from the house for heating or cooling. Inside the house they terminate at the return air vents.

Supply air ducts are the ducts that carry cooled or heated air from the air handler to the house. As you can see, the house, air handler and ductwork form a loop that works all the time whether the house is being cooled or heated.

When the thermostat calls for cooling or heating, the air handler kicks in and its blower starts sucking air from the house through the return air ducts. Depending on whether the air needs to be cooled or heated, it is moved across the cooling or heating coil where heat exchange takes place.

Before heating or cooling, the air is first passed through a filter where dust, lint, pollen and other impurities are removed. The air conditioned or heated air is then supplied back to the house through the supply air ducts.

Air handlers are also responsible for ventilation. Ventilation is the deliberate process of replacing stale indoor air with fresh outdoor air.

Ventilation is an important aspect of HVAC. For your comfort, not only do you want the air cooled/heated but you also need it to be fresh.

Recycling the same air over and over again can make it stale. Breathing, cooking, cleaning and other such activities lowers the quality of indoor air and hence the need for ventilation,

Ventilation can be achieved by simple actions such as opening doors and/or windows (natural ventilation). However, opening windows and doors will lower the efficiency or your cooling and heating systems.

As such, the air handler is connected to a vent which delivers fresh air from outside. Therefore, the air cooled by the air handler is from both the indoor air and outdoor air. The air is mixed, air conditioned and then supplied to your house.

But why not just draw 100% fresh air from outside and exhaust the stale indoor air? Well, that would be very expensive.

Assuming that it is during summer, the air outside although fresh would be quite hot. On the other hand, the indoor air will be stale but just warm. If you decided to draw 100% of air from outside, the system would need to work harder to cool it.

The harder a system works the less efficient it is and the more you pay in energy bills. Mixing the indoor air with outdoor air slightly lowers its temperature thereby saving cooling and heating costs.

Air Conditioners vs Air Handler vs Heat Pump

Most folks also have a hard a time understanding the difference between a heat pump and an air conditioner. After all, the 2 systems look the exact same way.

The difference between an air conditioner and a heat pump is that an air conditioner can only cool the house while a heat pump can cool and heat the house. ACs are mostly paired up with gas furnaces for heating while heat pump use air handlers for auxiliary heating.

Note: Heat pumps and air conditioners work the exact same way when cooling the house. Only the heating phase is different.

The type of heating offered by air handlers is in form of electrical resistance heating. That is good enough for heat pump’s auxiliary heating but not air conditioners.

Heating a whole house with electric power for a whole winter would be very expensive compared to a natural gas-powered furnace. That will always be the case unless electricity prices fall dramatically while those of natural gas go up.

Different from an air conditioner, a heat pump has a reversing valve that reverses the direction of flow of the refrigerant when being used to heat the house. That way, the heat pump can extract heat from the outside air and use it to heat the house.

A very cold refrigerant is pushed through the condenser coil outside the house where it absorbs heat from the cold air (it is possible) and then evaporates and flows out to the compressor.

Inside the compressor, the gas is compressed to increase its pressure, a process that also increases its temperature. A high-pressure and hot refrigerant gas is then delivered to the evaporator coil inside the house.

As I mentioned, the heat pump will be connected to an air handler. The air handler’s blower pulls cold air from the house and moves it across the coil.

The air absorbs heat from the refrigerant and that is how it gets heated. The heated air is then supplied back to the house.

When temperatures outside drop below 35/40 degrees, the heat pump can no longer extract heat from the air. At that time, auxiliary heating will come on in your thermostat.

When the auxiliary heating comes on, the air electric heat strips will be activated to complement the heat pump. Auxiliary heat will go off once the temperatures outside improve.


And basically that is the difference between an air conditioner and an air handler. Apart from that, I also hope that you now know the difference between an air conditioner and a heat pump, difference between heat pump and air handler and also the difference between an air handler and a furnace.