Frankencooler Ice Chest Air Conditioners

I’ve run out of room in my garage. A big part of this problem are the Frankencoolers clogging my shelves – large coolers take a lot of real estate. This led me to come up with a compact, portable device that could be paired with anything from a small, soft-sided cooler to the largest hard-sided ice chest providing all day/all night cooling. After numerous prototypes, countless hours in a sweltering garage, and six-figure credit card bills, I call the result ‘Blowbox,’ mainly because I couldn’t think of anything better.

I took everything that makes the Frankencooler design so effective – the best 200 CFM blower available, multiple high-quality heat exchangers, variable speed digital motor controller, absolute segregation of air and ice/water – and incorporated it into the smallest package I could. This unit plugs into a separate low-amp marine pump that can be placed in any container capable of holding ice/water. I use my BB with several different sized soft-sided coolers, depending on how long I need cooling. The Blowbox and my largest soft-sided cooler combined take only a foot of shelf space when not in use.

This design is powered by a 10′ 12V power plug for hours of operation from any car/plane/boat power socket, and is also power cell ready, accommodating our 4.6 Ah Bioenno Power lithium iron phosphate power cell in its internal tray for 1.5 – 2 hours of operation anywhere, or remove the tray and you have room for our massive 12 Ah power cell, providing over 6 hours of off-the-grid cooling when paired with a sufficient amount of ice.

Speaking of more ice, the Blowbox can also be used with any hard-sided cooler just by drilling two small holes for the pump tubes and small power plug to pass through. A couple of inexpensive plastic plugs reseals the cooler for non-Blowbox duties.

I fabricate several of the key components that make this patent-pending design possible, and because they are not available anywhere, plans come only with our Blowbox Component Package, which will be available very soon on this site. This package is our most complete – requiring only a few inexpensive supplies from Home Depot/Lowes to complete.

Oh yeah, it works awesome.

• One of the most common mistakes someone can make when building a Frankencooler is allowing air to get around the heat exchangers (radiators). When running, the blower(s) on a Frankencooler are working hard to pull air through multiple heat exchangers, and even a small gap can draw in hot air that can severely compromise the cooling effectiveness. A good quality, dense, foam tape is your best friend for sealing heat exchangers to surfaces. HVAC foil tape and silicone sealer are also handy in some applications.
• Even if you’re using a 12V power plug for juice, pay attention to manufacturers’ stated amperage draw specifications when choosing pumps and blowers for your project – lower is better. This is doubly critical when running off of a power cell/small battery as even .5 amp can make a big difference in running time.
• Keep the air chamber as small as possible. The area under the cooler lid and above the thermal barrier should be just big enough for the heat exchangers and tubing. Use 90-degree fittings on your heat exchangers to route water tubes more tightly, keeping the area as shallow as possible and allowing for a thicker insulative panel and more ice storage below.
• For maximum cool, do not operate blower(s) at full speed. Inline blowers of the type used by Frankencooler are powerful. Run at full speed, they can pull air through heat exchangers so fast that the transfer of heat (cold) is compromised. You’ll find that a range of around 50 – 75% blower speed provides a ‘sweet spot’ of strong airflow combined with maximum cooling.
• Consider the surface. The asphalt parking lot surface we tailgate on, even in the shade, is extremely hot. Being a cheapskate, my Frankencoolers are built from inexpensive coolers that don’t benefit from 3″ of solid foam insulation on their bottoms like a Yeti and the radiating heat takes a toll on the ice. Consider laying down a piece of foam board insulation like you used in your build underneath the cooler. If you don’t have foam board on hand, even a folded towel will help conserve ice.

Over the last couple of years, I’ve consulted with numerous individuals seeking a means to cool their tent or foam board shelter at the Burning Man Festival and other venues where gasoline is not available for individual use. So what does it take to cool a small shelter for days on end when the only thing available is ice? Answer: A big cooler, power pack, solar array and controller, insulated vinyl ducting, and special bezels that can be installed in the wall of a tent or hard-sided shelter.

Since cooling duration is wholly dependent on ice, you need a minimum of 40+ lbs of block ice to go all day in triple digits. I suggest at least a 100 Qt. high-quality ice chest for your Frankencooler, powered by a Bioenno renewable power pack with integrated solar controller connected to a small solar array. This setup will give you uninterrupted cooling in the hottest temps, as long as you feed it ice.

A flexible, insulated duct attached to an in-wall bezel at the bottom of the tent/shelter feeds cold air, while another in-wall bezel at the top of the structure carries return airflow to the inlet side of the Frankencooler. This setup effectively works the same as your home central AC unit. It goes without saying that a foam board shelter is easier to cool than a tent, and available kits make this the way to go, IMHO.

If you are going to spend days in blistering heat, don’t settle for a impotent fan or evaporative swamp cooler to keep you comfortable, build a genuine ice-fueled air conditioner utilizing the patent-pending Frankencooler design and enjoy the most effective off-the-grid cooling on the planet.

Every week I hear from people who who have already built an ice chest air conditioner yet are interested in building a Frankencooler(tm). The story is always the same: “In the video it looked like a good idea and it was cheap to build. It just didn’t work like I expected.”

From coolers containing a big snaking plastic tube hooked to a blower screwed to its side to giant coils of copper tube in front of box fans, you quickly find out the ‘good idea’ sucks as the ice quickly melts and the blowing air turns warm. There’s a good reason why office, home, and auto AC units blow air through a chilled aluminum or copper heat exchanger instead of employing a giant plastic tube immersed in Freon or chilled water.

The Frankencooler design isn’t magic – it utilizes the tried-and-true technology of chilling airflow that has been around for decades but does so in a way that is unique to any other portable ice water fueled cooler. Totally segregating airflow from ice/water storage provides the longest ice retention, while multiple heat exchangers work together to typically produce an incredible 50-degree temperature differential in 100+ degree temperatures. Regardless of price, no purpose-built cooler AC on the market can match Frankencooler’s effectiveness.

The downside to this kind of performance is the fact it’s more complicated and expensive than draping a big tube through a cooler, but the results speak for themselves. If you’re serious about escaping the heat, do it right the first time.

• Critical: Keep one or two gallons of water in your refrigerator to prime your Frankencooler as tap water will immediately melt a good amount of your ice, drastically cutting cooling duration.
• Use block ice whenever possible. A rough rule of thumb is one ten pound block per 1.5 hours of cooling (this obviously depends on outside temperature).
• Don’t run blowers at full speed, as there is a point where the air temperature will rise, as air is going through the heat exchangers too fast to effectively transfer cold. I’ve found that 60 – 75% blower speed is a good balance between airflow and temperature.
• If you are going to be using your cooler in a remote area where it is difficult for you to reach the motor controller to turn on/off/adjust blower speed (such as in a small aircraft). consider placing the motor controller on the end of a cable coming from the cooler. As long as you use adequate-sized wiring (I recommend 16 gauge for this), you can cable the controller 4′ – 5′ away from the cooler. Make sure you wrap your wiring in a protective sleeve.
• In addition, for remote operation of your cooler, Home Depot/Lowes also offers 48″ (and longer) 4″ flexible aluminum duct tubing you can use in place of the 24″ units I specify in my plans.
• After using your cooler outside, especially in dusty areas, wipe down the interior to keep it clean and prevent debris from accumulating in the heat exchangers.