Review: Zero Breeze Mark 3 Portable Air Conditioner

As the weather heats up, the trappings of summer arrive with it: swimsuits, mosquitoes, and, naturally, portable air conditioning.

Go-anywhere AC is now a thing, and in fact, I’ve been writing about it since 2019, when Zero Breeze released its first luggable, battery-powered air conditioning unit. A (minor) update arrived in 2022, but now version three is here. Conceptually, the Zero Breeze Mark 3 (Roman numerals begone!) remains the same as its forebears, though the design has been tidied up a bit, giving it a cleaner and more polished look. Nevertheless, it’s still a beast of a device that is hardly something that will live in your trunk just in case you take an impromptu trip to the beach.

Portable Air

Photograph: Chris Null

Measuring 22 x 10 x 12 inches (without the battery pack installed), the Mark 3 is a little larger than the Mark II and quite a bit heavier, now weighing 22 pounds compared to the Mark II’s 17 pounds. Clip on the enormous 1,022-Wh battery pack and you’re adding another 14 pounds to the rig, though that frees you from having to be near a power outlet if you want to cool down.

I complained in both of my earlier reviews that Zero Breeze’s approach to charging was a bit silly, because although the battery pack physically clips onto the bottom of the air conditioner, it uses a separate cable to attach to the air conditioner’s charging port. Incredibly, this is still the case, though you can at least now operate the Zero Breeze from battery power while it's simultaneously charging—something that wasn’t possible on previous iterations. (You still can’t run the Zero Breeze while charging if the battery is completely dead. It needs some juice, about a 50 percent charge, to get things going, after which it can run indefinitely.)

A new feature is that batteries can now be stacked and charged in sequence (as many as you like), each daisy-chained to the next, though at a minimum of $600 per battery, this can quickly get exorbitantly expensive. Each Mark 3 battery also has extra outputs that can be used for other devices—one USB-C port, one USB-A port, and a 12-volt DC socket. This is a downgrade from the Mark II battery, which has all of the above plus a second USB-A port. Why it was removed is a mystery.

Photograph: Chris Null

The unit still works well, arguably better than before, though this is difficult to quantify with certainty because testing conditions are variable. The Mark 3 blows very cold, very quickly, with the onboard thermostat (measuring the temperature of air being output) hitting 60 degrees in my tests within a minute. That tracks, because at 5,280 British thermal units (BTUs) of cooling power, it has more than double the cooling capacity of the Mark II.

In pretty much every dimension, it’s a bigger, punchier unit. At the same time, it doesn’t seem as loud as the rumbling Mark II did. Unfortunately, I don’t have a comparative measurement of noise to use as a benchmark, but at a reasonable 55 decibels measured 3 feet from the output fan, the Mark 3 felt far more comfortable to be around than previous iterations of the device.

Break the Ice

The Zero Breeze Mark 3 can be used as is, with no extra parts attached, but those with more complicated HVAC needs can use the three included, expandable ducts and various adapters to route hot and cold air in various ways. I won’t go into all the permutations here, but both front and rear have an outlet and an inlet; cool air is emitted from the front and heat is exhausted from the rear, while the two inlets are used for circulation.

For example, you can connect the cooling output and its corresponding inlet to ducts that lead to a tent while positioning the Mark 3 outside. This maximizes circulation and cooling power by recycling the cool air while allowing warm air to be expelled. You can also use the ducts to direct air further away from the unit, helping to reduce noise further. Unless you’re using the device outside, you will also need to use the included rubber tubing to direct the condensation the system creates to someplace you don’t want to get wet.

During my testing, I encountered a problem with the first Mark 3 unit I received, via a cryptic “E18” error on the device's front panel. The manual indicates E18 relates to a “water overflow alarm,” but Zero Breeze representatives weren’t forthcoming about what that meant or how to fix it, instead arranging for a replacement unit to be sent to me. (After this review was published, company reps explained that certain troubleshooting steps could have been taken, but replacing the unit was faster since I was writing a review.) I haven’t encountered E18 errors again or any other problems on the replacement device.

Photograph: Chris Null

The system is easy to use, though the included remote is more convenient than pressing buttons directly on the device, which are touch-sensitive and can be hard to engage. A thermostat still indicates the temperature set for outbound air, and a light ring around the output vent indicates, on a sliding color scale, whether it’s blowing hot or cold.

At full blast, I achieved just shy of five hours of running time from the Mark 3 via a fully charged battery—a significant upgrade over the roughly four hours on the Mark II. But there’s also the price to consider. Coughing up $1,300 gets you the Mark 3 bare, with no battery. Adding a single battery will knock it up to $1,900 (bought as a bundle). Compare that to the current price for the Mark II of $899 (no battery) and $1,274 (with battery). The boost in power is significant, but so is the upcharge, to the tune of a nearly 50 percent price hike.

I agree that it’s impossible to place value on comfort when you’re out in the elements, and if I were a regular outdoorsman, I might indeed find this a worthwhile investment if I had the lack of sense to frequently go camping during a heat wave. Surely there are other ways to keep cool, though, right? I guess what I’m trying to say is that even a cheap motel room comes with air conditioning.