Here are the pros and cons when using a ductless A/C unit

Feb 29, 2024, 3:00 PM

New AC unit sits outside by an old one....

Explore the benefits and drawbacks of ductless A/C units with Rosie on the House. (AP File Photo)

(AP File Photo)

Here at Rosie on the House, we get tons of calls from Arizona residents wanting to know if a Ductless A/C unit, sometimes called a Mini Split, is right for them. As you might expect, the answer is maybe. It depends on what your specific needs are.

What is a ductless A/C unit?

A typical Ductless A/C unit is installed with indoor and outdoor components in much the same way as your standard, whole house air conditioner. The inside portion of the system contains the coils that are filled with a refrigerant. A fan will pass warm room air over these coils, which absorb the heat, and the cooled air is blown into the room. The indoor unit is installed relatively close to the ceiling. The outdoor component is the condensing unit, which cools the refrigerant and releases heat that is absorbed from the room.

So far, this matches how your home’s HVAC unit works. The difference between the two systems is that with the whole house air conditioner, the ductwork in your home is utilized to distribute the cooler air throughout the house. The ductless unit pushes the cooler air directly into the intended room. Check out our blog on What Is A Mini Split and What Are The Benefits to learn more.

Let’s look at the advantages and disadvantages of installing a ductless A/C system at your house, home, castle, or cabin.

What are the pros of a ductless A/C unit?

A Ductless AC system offers several advantages. The most prominent advantage is that they allow you to control a specific room’s temperature. A homeowner might use this type of system in a room not connected to the home air-conditioning system or in a room with cooler temperature needs than the rest of the house. Willy Rodriguez of Day and Night Air Conditioning, Heating, Plumbing, & Water Treatment, a Rosie Certified Partner, offers other examples of why you might want to install such a system.

  • Cooling the garage | It’s a good choice for the garage. You can cool the room efficiently and add a place for a workshop or hobby area.
  • Remote buildings | These units work well for a “she shed” or any space completely remote from your house.
  • Additional cooling in one room | Perhaps you’d like to have the main bedroom cooler than the rest of the house for sleeping. Or maybe you’ve got a fully enclosed patio that would be more enjoyable if it were cooler.
  • Limited access to ductwork | This could be the case with a new addition or a house with a flat roof when the existing space or new addition has no room for ductwork.
  • No leaking ductwork | Without a duct system, there is no air leakage. The principal reason for an HVAC system’s inefficiency is ductwork air leakage or inadequately insulated ductwork passing through a hot space.
  • Dedicated air filter | Each unit has its’ own filter. These filters are typically easy to access, making them easy to wash, dry, and put back in place.

When you want to target an existing room with cooler air and your standard whole-home system is inaccessible, a ductless air conditioning unit is a good solution. Learn more about How To Maximize The Benefits Of A Mini-Split.

What are the cons of a ductless A/C unit?

With the advantages comes the disadvantages. We talked with Bryan Whitlock of Rosie on the House Certified Integrity Air Conditioning & Heating to get some of his expert insights on this topic. He agreed that there are many applications where ductless AC systems work well. If you are considering a ductless system to solve a current dilemma of your HVAC system, Bryan prefers to first look at any existing HVAC system to see if there are solutions before jumping to a ductless system. In his experience, working with the existing system may be the best choice.

Here are some points to ponder as you decide whether a Ductless A/C solution is for you:

  • Ductless units can be hard to repair | Not all brands are created equal, and the parts they need are difficult to obtain. Because of this, the entire unit will often need to be replaced when parts are unavailable. A costly fix!
  • Different brands are built utilizing various technologies | The challenge here is training the AC technicians to understand all the differences between the various units. This difficulty applies to installation as well as maintenance and repairs.
  • Air filtration | The efficiency of the HVAC system filtration is superior to that of ductless systems. Additional filtration for a ductless system will be needed to achieve the filtration level of an HVAC unit. This is an essential point if air purity is a consideration for you.

Can I install a ductless A/C unit or mini split myself?

If you are thinking of installing one of these yourself, here are a few more cautions for you:

  • Ductless systems require a permit to be installed.
  • A ductless system requires a dedicated electrical circuit for the unit.
  • Refrigerant is difficult to obtain.
  • Specialty tools needed include a flaring tool and a vacuum pump.

So, there you have it! We hope these guidelines move your decision-making along.

Join Rosie on the House every Saturday from 8 a.m.-11 a.m. on KTAR News 92.3 FM. If you’d like to send us questions or comments, email Follow us on X and “Like” us on Facebook. For more do-it-yourself tips, go to An Arizona home building and remodeling industry expert since 1988, Rosie Romero is the host of the syndicated Saturday morning Rosie on the House radio program. Call 888-767-4348 with questions and comments.

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Here are the pros and cons when using a ductless A/C unit