DIY Air-conditioned Car Setup so your Pup Stays Cool and Safe in Summer​

A stripped open car
DIY car setup: portable air conditioning unit in the back seat that cools the front seat dog spot and is partitioned off from rest of car, a car sun umbrella for critical shade, temperature alert device, and extra ice storage in the back.​

Takara’s separation anxiety in her older age compelled me to create a DIY setup that allowed me to keep her in my car at a safe temperature for extended periods. The car was always a safe place for her because in her experience I reliably returned to the car every time– unlike at home where a dog sitter might show up instead. ​

When my plans took me somewhere dogs weren’t allowed or where I knew Takara wouldn’t be comfortable (outdoor events in summer heat or big crowds) I was able to keep Takara in the car up to 10 hours a day (with pee breaks every 2-4 hours) and up to 30 degrees cooler than outdoor temperatures while getting temperature updates every 5 minutes. Missouri summers have high humidity with average temperatures in the 80s and 90s and often several consecutive days of 100-degree temperatures. So, if she was going to be in my car, I had to be sure she was comfortable and safe.​

This blog describes how I converted my car and, with the help of a friend, built a device to alert me of the car’s interior temperature. I put several months of work and research into making this setup effective and efficient so, if you are looking for something similar, I hope this saves you significant time that is better spent with your pup. The responsibility always rests on you to ensure the safety of your dog, but when done correctly this setup will allow your pup to be your year-round copilot even in summer months and not be anxious about being left at home.​

A dog in a car.
Takara (2018) sleeping comfortably in her dog spot cooled by the DIY air-conditioned car system during summer.​

Keeping your dog safe in your car during summer has become easier in the last few years with keyless ignitions and Tesla electric cars (i.e., “dog mode”). Cars with keyless ignitions allow you to park with the air conditioning running (which requires the engine to run), lock your car with your dog inside, and run your errand. This is handy for short errands, but you wouldn’t want to leave your dog for a full work day because the AC doesn’t run as cool when the car is parked for long periods and because running the engine with AC drains gas. Other critical disadvantages are that most cars’ engine will automatically shut off after a specified time (e.g., 30-40 minutes), and if the car were broken into it could be driven away with your dog inside.​

Tesla electric vehicles have climate control where owners can set the interior temperature of their car while it is parked. AC in electric cars draws directly from the battery so this will drain your main source of mileage. Depending on how often you recharge your electric car’s battery and how close you are to a charging station, keeping the climate control on for extended periods might not be an issue for you. An advantage of the climate control is that the car’s interior temperature can be monitored on your phone with the Tesla app. This allows the comfort of knowing at any point in time the real temperature your dog is exposed to. A drawback to this app is there is no fool-proof feature to ensure you are constantly aware of your car’s temperature and thus, your dog’s safety. When our day gets busy it’s easy to forget to regularly monitor an app without a reminder. ​

I don’t have keyless ignition or a Tesla car so I created my own AC setup and temperature alert system for my car (2013 Subaru). If you have constant access to your cell phone throughout the day, rather than having to remember to check your car’s internal temperature via an app or having the stress of your car engine turning off automatically after a certain time period, the temperature alert device I used automatically sends a temperature update every 5 minutes via text. So, as long as you look at your phone regularly throughout the day (which most of us already do) and have your phone set to notify you of incoming texts (e.g., low volume ring tone or vibrate mode), you will almost effortlessly know the safety and comfort of your dog. ​

There are 6 key components to this reliable and safe DIY air-conditioned car setup, but if you don’t have a temperature alert device then the rest of the setup is pointless; the AC system alone should not be relied upon to keep your dog safe. If possible, it’s best to keep this setup in place throughout the warm season rather than installing and removing repeatedly. In my case, about 2/3 of my car was converted to the cooled area and extra ice storage. This meant I could carry one passenger behind the driver’s seat plus Takara in the front passenger seat, at most. Also, when first using this system, always have a backup plan until you iron out the kinks, such as taking your dog back home, running your car’s AC (and thus, engine), or bringing your pup into the building with you. This setup isn’t for everyone’s lifestyle, but it’s reliable and liberating for those whose lifestyle it does suit. ​

Components of the temperature alert device
Components of the temperature alert device (without a casing) and wifi hotspot to keep you updated on your pup’s safety and comfort.​

Key Components and Materials:​

1. Designated dog spot (“cooled area”)​

  • Area in the car that is comfortable for your dog for long periods and has easy access in and out of the car multiple times a day ​
  • Secured water bowl ​

2. Portable Air Conditioning Cooler​

3. Frame and partition​

  • Frame created from telescoping poles or similar to hang the partition​
  • Partition (blanket covered in plastic) to enclose the cooled area ​
  • Zip ties​

4. Extra ice storage and supply

  • 2 extra coolers (about 50-quart size each) for extra ice storage​
  • Cool gel and plastic containers to make reusable ice packs​
  • Freezer space to make ice blocks and refreeze ice packs (if your pup will stay in the car routinely, investing in a large freezer is highly recommended)​

5. Shade

  • Car sun umbrella and bungee cords (required if you don’t have access to constant full shade throughout the day such as a covered parking garage, full mature trees, or other solid shade) ​
  • Custom fit Sunshade heat shield for windshield ​
  • Foldable sunshades for remaining car windows​

6. Temperature alert device (TempAlert)

  • Temperature alert device and small portable battery​
  • MiFi device with SIM card to run temperature sensor​

1. Designated dog spot​

A dog sitting in a car seat.
Takara’s (2018) designated dog spot was the front passenger seat with access to drinking water and easy access in and out of the car.​

Designate an area in your car that is comfortable for your dog for long periods and where she has easy access to drinking water that won’t spill if bumped or stepped on. This area will be partitioned to create the cooled area; the area your portable AC unit will work to keep cooler than the rest of your car. If you use a crate as the dog spot, it should be large enough so your dog can easily turn around and stretch in the downward dog position. Remember to include plenty of comfortable bedding, depending on the condition of your pup’s joints. Placing a bedsheet (60% cotton, 40% polyester works well) over your dog’s bedding can help keep their bedding surface cooler, plus it is easy to throw in the wash. ​

Situate the dog spot so your pup has easy access in and out of the car many times a day for pee breaks and walks. If the dog spot is a crate, position the crate door so you don’t have to move the crate or move stuff out of the way to let your dog in and out of the car. In my case, the dog spot was the front passenger seat, so there was easy access simply by opening the passenger door. ​

Modified metal stand with plastic bowl
Modified metal stand with plastic bowl support to hold water bowl which was easily removed to empty prior to driving away and to clean. ​

Water access. It’s important to give your dog access to drinking water throughout the day, which means the water bowl has to be within the cooled area. I modified a wire shelf stand, attached a plastic mixing bowl with zip ties, and placed it between the two front seats so it couldn’t spill. Takara’s drinking bowl sat inside the plastic bowl and could easily be removed to toss the water before we drove away or for washing. ​

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2. Portable Air Conditioning Cooler

The cooler opened and closed.
GoCool portable AC unit (corrugated hub adapter not included) without modifications. DIY modifications were essential for reliable and efficient cooling of the dog spot.​

Takara was a short-haired dog and around 50 lbs. It was too warm for her in my car at about 75 degrees F (she would pant) so my goal was to maintain a temperature of 65 degrees or below as long as possible. Your dog’s breed, hair length, and underlying medical conditions are important for determining when it is too warm for your dog in your car. In my opinion, temperatures over 75 degrees F (80 degrees F max) are too warm for any dog, maybe with the exception of hairless breeds. ​

I bought a portable electric air conditioning cooler that uses ice and water to cool the enclosed designated dog spot. In my case, the cooler was placed in the rear passenger seat where it could be easily taken in and out to replace the ice supply. I recommend a GoCool cooler  (http://thetentairconditioner.com/gocool-portable-air-conditioner/) with DIY modifications to maximize cooling time. Once I figured out the cooler’s nuances and modified the interior so ice melt was more efficient and reliable, it fit my need nicely. To modify your GoCool to optimize cooling and extend your ice supply, click here. This brand cooler was chosen because: ​

  • Low energy requirement (1.6 amps; could run on 12 V DC AGM battery)​
  • Compressor that dehumidifies air to prevent condensation in the car ​
  • Air coils that cool the air rather than just a fan that blows over ice​
  • No need to crack open a car window for air circulation​
  • No chemicals (freon)​
  • Compact enough for easy loading/unloading at my rear passenger door (35-lbs unit)​
  • Responsive and very helpful customer service
AGM batteries
AGM batteries are significantly safer for the car AC setup than lead-acid batteries. ​

12V AGM battery. You will need to invest in an AGM (Absorbent glass mat) 12V deep cycle battery. AGM batteries are different from normal lead-acid 12 V batteries, such as that in your car, and are safe to run in enclosed spaces (normal car batteries are not). AGM batteries are more expensive but do not pose a danger when tipped, they charge faster, run about 13-16 hours, are maintenance-free, and the discharge is not harmful to you or your pup. (To learn more about different types of batteries: https://www.energymatters.com.au/components/batteries/#agm-batteries). I bought an Exide Edge AGM battery rated at 75 Ah @ 20HRS, from a local boat supply store.

Battery connected to inverter
Battery connected to inverter which provides power to AC unit.​
Battery charger
Battery charger to replenish AGM battery power.​

An inverter creates the necessary connection between the cooler and the battery to power the cooler using a standard 3-prong power cord. At the same boat supply store, I bought a 400 W inverter and mounted it on my car’s interior rear wheel well with Velcro close to where the battery sat. At the end of the day, I’d charge the battery overnight with a 1.25 Amp charger.

Six-wheel luggage cart
Six-wheel luggage cart to conveniently carry battery long distances.​

When my travels required a hotel stay or an overnight with friends and I still planned to use the AC setup, I hauled the heavy battery indoors to charge overnight using a portable luggage cart with wheels that move 360 degrees, which was very convenient. Simply strap down the battery with bungee cords if you’ll be rolling over bumpy sidewalks. (https://www.amazon.com/gp/product/B01MSMVJY6/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1).

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3. Frame and Partition​

The portable AC cooler was not powerful enough to maintain a temperature of 65 degrees F or less throughout the entire car, thus a partitioned area is needed. You want to build an enclosure that is sturdy and not easily knocked over or damaged by your pup especially if they are not in a crate. The frame and partition enclose the area to be cooled– the designated dog spot with drinking water access and the cooler. It is advised to include the cooler in this area because the cooler pulls air from the immediate surroundings into the coils to cool; the cooler the air is to begin with the longer your ice supply will last. Likewise, the smaller the area you enclose, the better the cooling effect will be and the longer your ice supply. ​

Empty car
Area to enclose is front and rear passenger seats.​
Central support to hang partition
Central support to hang partition (long leg of “L”.​
Baby gate section to hang partition
Baby gate section to hang partition (short leg of “L”).​

You can use any number of make-do materials to create the frame and partition. For my setup, I created an L-shape ceiling rung to hang a partition that ran from my windshield, between the front seats, and around the cooler in the back seat. First, I placed a central support (empty plastic roll of window film) where the “L” legs meet to hold the rods. Next, I used a curtain rod that extended from my rearview mirror to the central support (attached with zip ties) for the long “L” leg and a section of a child gate for the short “L” leg, supported by a bar placed across the cargo area. In my case, I kept the frame and partition installed all summer because it was inconvenient to frequently remove and replace. Plywood might also work to enclose an area, but I wouldn’t recommend insulation panels because they squeak when you drive which can be annoying and the seams were difficult to keep sealed (cool air can escape through open seams).​

Insulated partition
Insulated partition was a blanket wrapped in plastic and attached to the rung with zip ties.​
Partition attached
Partition attached to frame and extending to car’s ceiling.​

Partition. For the partition I wrapped a layer of plastic over a blanket which seemed to adequately insulate, keeping cool air on one side of the partition and warm air on the another. Zip tie gussets were created at the partition edge from where it hung on the curtain rod. The car ceiling curves upward at the car’s center which created a larger gap from here to the curtain rod. To maintain efficient cooling, I added more plastic “frills” at the top of the partition in this area to block the gap. ​

Partition attached to short side of L-frame
Partition attached to short side of L-frame.​
Clear plastic partition
Clear plastic partition extending along windshield for a “sealed” enclosure and that allowed Takara more visibility. ​

The blanket partition did not extend between the front seats to the windshield; it was just around the cooler. For between the front seats I used a clear plastic shower curtain. It was efficient insulation and allowed Takara more visibility. I also cut it long enough to block air gaps at the rear and front floorboards and to extend along the dashboard to the bottom of the windshield. Of course, during driving I pushed this section of the partition back. I held the plastic curtain in place over the dashboard with a bean bag and also tucked it in between the front seat and console to keep the cool air within the enclosed area. Occasionally, Takara would nose her way to the driver’s seat, opening the partition and letting cool air escape which I could detect on the temperature alert device. If you aren’t in an area where you can easily replace the partition, I suggest making your designated dog spot more sturdy (such as a dog crate). ​

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4. Extra Ice Supply and Storage​

Large and small freezer
Large and small freezer designated to making a week’s supply of melting ice and ice packs.​

For an 8-hour workday I typically went through 3 rounds of ice and ice packs, depending on temperature and humidity. On especially humid days the cooler burns through ice faster so if I ran out, I made a run to a nearby gas station or would run my car’s engine and AC until quitting time. ​

I quickly decided after working through the cooler’s nuances to make my own ice blocks because their availability at gas stations wasn’t reliable, they last a lot longer than ice cubes, and it was significantly more convenient to control my own supply. I dedicated a small and large freezer to just making ice blocks and ice packs. If you plan to run your AC setup on a regular basis for a long period, I highly recommend investing in a large freezer.​

Containers used to make melting ice and ice packs
Containers used to make melting ice and ice packs.​

There are two parts to replenishing the AC cooler (based on DIY modifications): ice for melting (which creates the air-conditioned air) and ice packs for keeping the melted water cold (to extend the life of the ice for melting). To make ice blocks for melting, I used 4-quart and 1-quart reusable plastic containers of a specific shape to fit in the cooler and melt evenly. For each replenishing cycle I used two 4-quart ice blocks, one to two 1-quart ice blocks for the melting ice.

To make the ice packs that keep melted water cold, I used a combination of 2-liter and 1.25-liter soda containers, 4-quart Gatorade containers, and 4-quart Tupperware containers with leak-proof lids. Ice packs were made with KoolerGel by TBK Industries LLC (https://www.koolerkube.com/product-page/koolergel-the-ice-extender-makes-ice-last-up-to-50-longer) which keeps the ice packs colder longer and shortens the time to refreeze. Each replenishing cycle consisted of one Gatorade or 4-quart Tupperware container, one 2-liter and one 1.25-liter soda bottles.​

Extra storage of melting ice and ice pack
Extra storage of melting ice and ice pack in cooler for replenishment throughout the day.​

I let ice for melting freeze for at least 72 hours to be sure it was frozen solid. Thus, I prepared 3 days worth of 3 rounds of AC cooler replenishment at a time between my two freezers. When draining the water from the cooler between replenishing, I recycled the water by putting it into empty containers for freezing (since it wasn’t being used for drinking water). Sometimes, I used this water to wet down Takara on a walk to cool her off. ​

Refreezable ice packs
Refreezable ice packs helped keep extra ice storage in coolers colder longer.​

My day started with round 1 of ice and ice packs in the AC cooler and rounds 2 and 3 stored in standard 48-quart sized coolers. To extend the life of the replenishments I used common (not made with KoolGel) refreezable ice packs to keep the extra ice frozen longer (https://arctic-ice.com/products/alaskan-series). Try not to open an ice storage cooler until you are ready to use the ice. Also, turn on your car’s AC while exchanging ice so your cooler does not have to work so hard to bring it back down to a comfortable temperature once it’s replenished.​

Two 48-quart coolers
Two 48-quart coolers in back of car with rounds 2 and 3 of AC cooler ice replenishment. AGM battery is located behind the cooler on the right. ​

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5. Shade

Yeege sun shade for cars
Yeege sun shade for cars was light but didn’t provide enough shade coverage or hold up to wind well.​

Shade is one of the critical components to the success of the air conditioning setup and keeping your pup safe. I guarantee your partitioned area will not be maintained at a safe temperature without some form of external car shade. The best shade is a covered parking garage or carport where your car is 100% out of direct sunlight and shade coverage does not change as the sun crosses the sky. The next best option is under a thick tree canopy. A building shadow works but in summer when the sun is high in the sky, you often won’t find a building’s shadow that lasts for an extended period of time. I used a car sun umbrella and a couple times a day during Takara’s pee breaks, rotated the angle I was parked to minimize the surface area of direct sunlight on my car. ​

Mynew Carport provided excellent shade coverage
Mynew Carport provided excellent shade coverage but needed extra bungees to stabilize.​

I tried 3 different car sun umbrellas, all of which are discontinued today. However, a search online for “car sun umbrella” will take you to similar available items. The first umbrella I tried was a YEEGE Universal Fit Car Sun Shade Canopy Cover- Nylon (bought on Amazon, sold by Sunclose) and was 126 x 86 x 17 inches. It was compact and opened/closed like a typical rain umbrella but did not provide enough shade coverage so the cooler could not maintain a low enough temperature inside the car. Also, the umbrella didn’t stand up well to the wind. On windy days the joints twisted and detached, breaking in the process. There were replacement parts but they were extremely hard to replace.

DIY platform on top of car
DIY platform on top of car to raise the sun shade while opening/closing and prevent interference with car roof.​

The second umbrella provided full car coverage and was battery powered so it opened/closed with a remote, which was handy. However, I had to build a small platform about 6” off the roof of my car because a section of the jointed arms were too long to open on a flat surface. The umbrella was called Mynew Carport Automatic Car Tent Sun Shade Canopy (bought on Amazon, sold by HJexpress) and was 82 x 157 inches. Learning from the first umbrella that wind is ruthless, I attached bungee cords midway up the arm at the 4 corners of the umbrella and hooked them under my wheel wells and to the side mirrors. This was very effective except in high winds or on stormy days.​

Mynew Carport
Mynew Carport fit nicely in the back of the car on top of extra ice storage coolers.​

The 3rd car umbrella was a replacement for the 2nd (also a Mynew brand) after forgetting the remote on the top of my car and driving away. Impressively, it still worked after being run over by a couple cars but the umbrella didn’t function without the remote so I decided to not risk the damage getting worse and replaced it. The company by then had modified the design and I no longer needed the platform on the top of my car to open/close the umbrella. However, the newly designed umbrella frame was much more flimsy and snapped often in the wind despite being secured with bungee cords. Fortunately, not all snaps resulted in damage, but eventually, the damage was irreparable and compromised full shade.​

sun shade heat shield
A sun shade heat shield works well for keeping out radiant heat on the largest glass surface of your car (pictured here with corrugations resulting from years of use).​

Exterior shade is critical and so is keeping out radiant heat that easily transfers through glass. Using window shades in the interior of your car helps keep your cooled area cooler for longer. The windshield is especially important to cover. I recommend buying a custom fit sun shade heat shield (http://www.intro-techautomotive.com/sunshade.html) for your windshield to maximize coverage and provide added insulation. For the side and rear windows I used convenient foldable sunshades (silver side facing out) and took these off and on each time I drove and parked (https://www.amazon.com/gp/product/B010AKHH1E/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1) (bought on Amazon, by Idealgo).​

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6. Temperature Alert Device (TempAlert)​

Don’t bother with any of the above 5 components unless you also have a device that regularly notifies you of the temperature inside your car. Never risk your dog’s safety; it’s not worth the cost.

A good friend helped me create the early version of the TempAlert using open-source code. That code has been converted to another program (Arduino) so that anyone with a laptop or PC can access it. I share that code with a list of materials and instructions so you can to build your own TempAlert monitor your pup’s safety. If you run into difficulty at any step in building your own device, I highly recommend visiting your local makerspace for assistance. If you don’t have time or don’t want to build your own, you can order one from us.​

The temperature sensor of the TempAlert needs to be placed in an area that will accurately reflect the temperature of your dog spot. It also needs to be in a location that minimizes risk of your pup chewing it, moving it, or laying on it. Do not place the sensor directly in front of the AC cooler’s air flow which would make the temperature of the entire cooled area seem cooler than actual. I put my sensor between the dashboard and Takara’s bedding, which worked well (AC cooler air flow coming from behind the front passenger seat). I also mounted a store-bought temperature sensor on the dashboard to periodically cross-check the temperature reading of my device (always good to have backups). ​

The code for the TempAlert is written so that temperature data is delivered every 5 minutes. I chose 5-minute alerts because this is the maximum lapsed time I felt comfortable knowing the change in temperature. Temperatures in cars can climb dangerously high in minutes and I needed to be able to monitor the temperature trend over short time increments for peace of mind.​

Location of the TempAlert temperature sensor
Location of the TempAlert’s temperature sensor without a casing on the center console and store-bought temperature device above glove compartment (for cross-checking temperature readings) (2018).​

MiFi device. For the two summers Takara commuted daily with me in my car, my wifi hotspot was an old cell phone that I placed in the dashboard cubby hole next to the TempAlert. The sole purpose of the phone was to transmit texts from the TempAlert thus the battery life lasted all day (fully charging every night). If you don’t have an old phone, you can order jetpacks or MiFi devices online. A key feature is that the hotspot must be able to connect to the internet and therefore must have a SIM card.​

Regardless of the wifi hotspot you use, you will have to go through a provider to get service. Your current cell phone provider probably has their own brand of wifi hotspot device that is cheaper for current customers. Having unlimited texting on your phone plan is highly recommended, because the TempAlert is programmed to send you a text every 5 minutes.​

TempAlert without casing
TempAlert without casing (quarter pictured for scale), with MIFI device and portable battery needed to operate TempAlert.​

The TempAlert needs a power source while in your car. I used a portable rechargeable battery, fully charged every night, which lasted all day. Consider having 2 portable batteries in case you forget to charge one or the charge had a bad connection. I found Anker brand batteries to be reliable (https://www.amazon.com/Anker-PowerCore-Ultra-Compact-High-Speed-Technology/dp/B0194WDVHI/ref=sr_1_3?crid=1I93E1DMGK2E8&dchild=1&keywords=anker+portable+charger&qid=1589753118&sprefix=anker%2Caps%2C181&sr=8-3).

Many cars nowadays have built-in WiFi hotspots and USB ports to power devices but typically the ignition has to be in the “Run” or “Accessory” position to activate the WiFi and USB ports. You will have to be familiar with your own car’s infotainment system to know when Wifi is active and whether using your car’s battery to run a temperature device is a better option than a pocket rechargeable battery. ​

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Helpful links about wifi hotspots:

https://www.my-webspot.com/blog/what-is-a-pocket-wifi/

https://www.computerworld.com/article/2499772/how-to-use-a-smartphone-as-a-mobile-hotspot.html