What’s the Best Air Conditioner for a Garage?

Installing an Air Conditioner in Your Garage? Here are Your Options and Approximate Costs

My two-car garage has everything but a car in it. That’s because I spend a lot of time in my garage working on my motorcycles and various home improvement projects. I would say my garage looks like what would happen if a hardware store and the tool department at Home Depot had a baby.

I know I’m not alone because my company, Magic Touch Mechanical, gets several calls a week from people interested in the best way to cool their garage. We’ve installed hundreds of new AC units in garages that were being used for wood shops, sewing rooms, and even food pantries. We even had a client that converted a 3-car garage to a “dog room” for her very large, and very spoiled fur babies.

Never Connect Your Garage to Your Home Air Conditioning Unit

Before I go any further, for your own safety, I want to quickly cover how you should never add ductwork from your home’s central air conditioning system to your garage.

DO NOT connect to any of the duct work that provides air conditioning for the living area of your home to your garage. First of all, it’s a major building code violation here in Arizona – and I would assume everywhere else in the United States.

Second, the reason it’s illegal is: Air conditioning your garage using air ducts connected to your home could prove fatal, as it creates a path for deadly carbon monoxide to enter your home.

Carbon monoxide (CO) is a poisonous, odorless, colorless, tasteless gas that is less dense than the air around it and claims the lives of about 500 people a year in the U.S. alone – mostly in their homes.

Even if you do not have a gas water heater, furnace, or other gas appliance in your garage that produces CO; just pulling a car into your garage and shutting it off immediately is enough to allow fatal levels of CO to enter your home.

Now that you know what not to do, let’s talk about some safe ways to add air conditioning (and possibly heating) to your garage.


Different Ways to Cool a Garage with Air Conditioning

There are a number of ways you can add air conditioning to a garage, each with pro’s and con’s which we’ll look at. The size of your garage, contents, how much time you plan to spend in there, and what you will be doing in there need to be considered to determine which is best for you.

We also need to cover how well your garage is insulated and how airtight (or loose) it is to make the right choice, so we’ll talk about that as well.


Cooling a Garage with a Ductless Air Conditioner

A ductless air conditioner, also known as a mini split air conditioner or ductless mini-split, is arguably the best way to add AC to a garage, however it is also undoubtedly the most expensive option.

Interested in how much a ductless air conditioner costs to install? Check out our article Ductless AC – How Much Does it Cost?

Here in Mesa, AZ the average cost to have a quality ductless mini-split air conditioner in a garage is in the low $4,000 range, and mid $4,000 range for a ductless heat pump. I can only speak for my company, Magic Touch Mechanical, but that includes a high-end brand with a 12-year warranty (we are a Mitsubishi Ductless Diamond Dealer which qualifies for the extended 12-year warranty), installation, all the electrical work, condensate drain line, condenser pad, remote control thermostat, and all the ancillary items needed to complete the project.

There are cheaper brands on the market like Gree, Midea, and Fujitsu to name a few, however for the few hundred dollars difference, I personally think the value is there to upgrade to a Mitsubishi – you get what you pay for.



Benefits of Using a Ductless Mini Split Air Conditioner in a Garage


The Pros of a quality ductless air conditioner (assuming proper design and installation):

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    Will last even longer than most home central air conditioners

  • Can add “permanent” conditioned square footage to your home
  • Is one of the most efficient ways to air condition; with SEER and EER efficiency ratings significantly higher than most other types of air conditioners
  • Are extremely quiet
  • Have a small footprint so won’t take up a lot of valuable wall space
  • Do not sacrifice security. Unlike window air conditioners, ductless units do not require cutting a large whole in the wall that a burglar could use as an entry point.
  • Ability to both heat and cool your garage
  • Properly designed, can maintain the most comfortably (can maintain 75 degrees when the ambient temperature is 110F) *

*Assumes certain insulation values.


The Cons of a ductless air conditioner:

  • Most expensive option


  • Requires professional installation (beware of buying a machine like this online – it may seem like a way to save, but rarely ends up that way)


  • Can be removed, but in most cases becomes a permanent fixture of the home


Cooling a Garage with a Portable Air Conditioner

My company owns six portable air conditioners. We use them as loaners for Magic Touch Mechanical clients who are waiting for a special-order part to arrive, or who are waiting for a new central AC unit to be installed. We provide portables as a value-added thank you for clients who do business with us.

On average we get about three years out of a portable unit before it needs to be replaced. Granted these units are getting moved and knocked around quite a bit which doesn’t help with their disappointing reliability but considering their cost I know I for one would like to get more than a few years out of them…especially because we need to keep six of them in rotation.

We buy a mid-range model for our loaners which produces 1-ton of air conditioning for roughly $450. Four-hundred-fifty clams is a heck of a lot less than the $4k to have a ductless unit installed, but before you run out and get one or two – they don’t come without pain-points.

Whereas the ductless system is discreet, quiet, powerful, and reliable; portable AC’s are none if the above. They work well as good spot coolers in a pinch and on occasion but aren’t really a good everyday solution.

Perhaps the biggest inconveniences with portable AC’s have to do with their footprint and the need to run an exhaust hose outside to expel the heat the unit is pulling out of the room. Not only are the exhaust hoses unsightly and cumbersome, most garages do not have a window the exhaust hose can run out of. Having to crack a garage door 6” to exhaust the heat, may just let in more ambient heat than the unit can keep up with.


The Pros of using a portable air conditioner to cool your garage:

  • A fraction of the cost of the best solution
  • Does not require professional installation
  • Can be plugged into a standard wall outlet (note: more than one unit will most likely cause circuit overload)
  • Pro: Quieter than most window units / Con: Significantly louder than almost all ductless units
  • Can be moved to another area for spot cooling if needed


The Cons of using a portable air conditioner to cool your garage:

  • Poor durability. These units only last 2-3 years under constant use
  • Very inefficient and expensive to operate
  • Cumbersome large footprint uses a lot of space
  • Requires somewhere to exhaust the hot air pulled out of the room
  • Requires manually draining a condensate pan or running a drain hose across the floor to somewhere
  • May struggle to keep up with the heat load especially on hot days
  • Repair options few and far between. Most HVAC Contractors do not work on portable air conditioners.
  • Mostly cooling only options, hard to find heating and cooling models



Cooling a Garage with a Window Air Conditioner

I grew up in a home in New York built in the mid 1960’s. We didn’t have central air conditioning, only central heating. Every summer my father would put a window unit in two rooms – the living room, and the master bedroom (the rest of us would suffer on muggy summer nights).

Being one of four kids, we would fight to be sitting as close to the air conditioner as possible – and second place would get to sit in front of the box fan! Once you got more than 7-8’ away from the window unit, you may have well been in another room. I’m reminded of the old saying, “It’s like peeing in the ocean.” That little air conditioner could never keep up with the heat load and really only dropped the room temperature a few degrees at best. That was in New York, not in Arizona where our summer temperatures can really hit as high as 120 degrees.

Of the three ways to air condition a garage we discussed so far, this is probably the least feasible, but also probably the least expensive (upfront). Installing a window air conditioner is okay if you really just want to drop the temperature a few degrees, but I wouldn’t expect to spend any length of time in the garage utilizing this method.

The main reason a window or wall unit is probably the least practical way to cool your garage, is the fact that it requires you to cut a large hole in the wall. Since your garage wall is most likely in the front of your home, it will most likely look cheap and unsightly. However, my biggest concern with this is the security issue it creates. Burglars know if they push the air conditioner through the hole, they now have a way to climb into your home!

Window air conditioners are also extremely inefficient, loud, and difficult if not impossible to find repair parts or technicians for.


The Pros of using a window air conditioner to cool your garage:

  • A fraction of the cost of the best solution, and cheaper than a portable unit
  • Does not require professional installation (if you are handy)
  • Can be plugged into a standard wall outlet (note: more than one unit will most likely cause circuit overload)


The Cons of using a window air conditioner to cool your garage:

  • Requires cutting a large hole in a garage wall
  • Hole size in the wall becomes an issue when needing to replace window unit with another – difficult to match footprint leaving too large a hole or having to cut more
  • Creates a security issue
  • Let’s face it, they’re ugly and loud!
  • May not produce the results most expect


Cooling a Garage with an Evaporative Cooler AKA Swamp Cooler

Believe it or not, evaporative cooling can work very well in bringing down room temperatures and are widely used in commercial garages and machine shops until the humidity reaches a certain point – after which they are no longer effective.

We typically reach a point in early July where evaporative cooling is no longer an option for the rest of the summer which as we know in Phoenix, lasts through September – and for the last couple of years almost until Halloween.

Evaporative cooling also needs a place to move the hot air so either the garage door needs to remain open or some other way to let the air escape needs to be installed – which gets back to the security issue.

Evaporative coolers also require a regular water source and are high maintenance, requiring specific start-up and shut-down procedures, media pad replacement, float replacement, etc. I thought evaporative cooling deserved an “honorable mention” but they can’t technically be classified in the same group as the other air conditioners which work when you need them most whereas swamp coolers are worthless for the entire second half of the summer season.


Is Cooling Your Garage with Air Conditioning Expensive?

Keep in mind, 99% of the time your garage is not insulated because it was not intended to be conditioned. In most cases, garages will share one common-wall with your home and that wall will be insulated as it’s technically an “exterior” wall of the conditioned part of your home. The other two walls are rarely insulated, and you may or may not have an insulated garage door.

More importantly, the attic space above your garage ceiling is typically not insulated and this is the one you really want to insulate if you are planning to install an air conditioner in your garage. The exception being if you have a flat roof above your garage, in which case you may have some added R-Value from the roofing materials – especially if it’s a foam roof. Luckily, it’s not very expensive to insulate the attic above your garage, and can typically be done for hundreds of dollars, not thousands.

It is possible to insulate the walls of your garage as well, using a spray foam process known as “drill and fill”, however the return on investment does not typically warrant spending the money on it.

If you already have an insulated garage door, you are ahead of the game. If not, I typically recommend installing a foam panel kit especially if the garage door is South or West facing.

Much in the same way you want to make sure your home is well insulated to keep the cool air in during the summer and warm air in during the winter, you can keep your utility costs down by making your garage as efficient as possible if you plan on cooling and heating it.

Ductless air conditioners and heat pumps are typically much more efficient than even most newer central air conditioners so won’t break the bank even on less efficient garages. Window units and portable units however do not have to meet any efficiency standards and tend to be pretty expensive to operate…especially if they are running constantly to contend with the heat.


Where Can I Buy an Air Conditioner for my Garage?

If you are looking for a “plug and play” AC like a portable air conditioner or window unit, I have found the best deals for our portable units on Amazon. I tend to buy ours at the end of the cooling season when demand goes down to get the best deals. If it’s an evaporative cooler you’re after, most HVAC Contractors sell and install them including mine.

If you are looking to have a ductless air conditioner or heat pump installed, and live outside of the Phoenix-Metro area, I recommend using the “Dealer Locator” on the Mitsubishi Electric ductless air conditioning website. Look for a “Mitsubishi Diamond Dealer” in your area. Diamond Dealers are factory trained and certified which gives you the end user several advantages including an extended warranty of 12-years on all parts.

More importantly, Diamond Dealers have to certify by traveling to Mitsubishi’s training center for hands on training. Recertification is required every two-years. This equipment is high-tech and a proper installation is the most important part of the equation. I have seen many a nightmare created from this equipment being installed improperly – usually because the homeowner attempted to save some money by purchasing the equipment online and hiring unqualified contractors to install it. Just like the equipment itself, you get what you pay for.

If you live in or near Phoenix, Mesa, Scottsdale, Peoria or surrounding cities, you are in our (Magic Touch Mechanical) service area and have already found the best Mitsubishi Ductless Diamond Dealer around! Give us a call, text, or signup online for a free no-obligation quote!