June 2nd, 2026
If you’ve ever parked a horse trailer in a warm parking lot and opened the door to feel a wave of heat roll into the trailer, you probably understand why using air conditioning systems for horse trailers is so important. Trailer interiors can reach temperatures 20 degrees Fahrenheit warmer than the exterior temperature. As soon as the interior temperature reaches between 75 and 90 degrees and the humidity level increases, there is significant potential for severe heat stress. We’ll explain how to determine the correct air conditioning unit size for your trailer, discuss the different types of systems available, identify key characteristics of each type of unit, describe approximate costs associated with purchasing and installing each type of unit, and suggest methods for maintaining a comfortable environment for your horses when traveling. Whether you’re hauling two horses to a local competition or permanently residing in a fully equipped living quarters trailer, the concepts described here apply equally.
Horses are large mammals whose metabolic processes produce a substantial amount of body heat. When confined in a small trailer with little to no ventilation, the resulting buildup of body heat has no place to escape. Studies have demonstrated that horses confined in unventilated trailers exhibit increased heart rates and elevated levels of stress hormones when compared to horses transported in adequately ventilated spaces. This information should be considered when evaluating your trailer’s ventilation capabilities.
While most trailers contain design elements that facilitate cross ventilation (drop-down windows, roof vents, etc.) and improve ventilation performance (insulated roof/ceiling assemblies), they generally lack adequate ventilation when stationary (i.e., stopped). At rest stops in the middle of July in Texas or after arriving at a competition venue and remaining stationary for several hours, ventilation is insufficient to maintain a safe internal environment. Therefore, an air conditioning system is required to augment ventilation when stationary. An AC is a supplementary component to natural ventilation, not a replacement for it.
The British Thermal Unit (BTU) represents a measurement of an air conditioning unit’s ability to remove heat from its surroundings. In general terms, more BTUs translate directly to greater cooling capacity. Conversely, if an air conditioner is undersized relative to the trailer’s cooling requirements, the unit will continuously operate without reaching the desired interior temperatures. Similarly, oversized units will excessively dehumidify and cycle erratically, wasting energy.
Furrion manufacturing company recommends using 20 BTUs per square foot of interior space as a rough estimate for determining the necessary cooling capacity of an air conditioner. To illustrate this concept:
As previously mentioned, the above calculation serves merely as a starting point. In reality, actual cooling loads are frequently substantially greater than the calculated BTUs due to direct sunlight absorption on aluminum roofs, high-desert environments, poor insulation in the trailer, and/or transporting multiple horses in close proximity.
In virtually every instance, owners of mid-size trailers utilize 9500-15000 BTU AC units, with 13500 BTU units being by far the most commonly utilized. However, there are times when an owner may choose to install either a larger unit (e.g., 15000 BTU), depending upon his/her specific needs, including hauling in extreme heat, operating in arid environments, or possessing a larger-than-average trailer. Alternatively, owners utilizing smaller trailers or who prefer a window-mounted unit may opt for a unit producing fewer BTUs (approximately 5000-6000 BTU).
Rv-style roof-mounted air conditioners are currently the most popular solution for horse trailers with living quarters. These units attach to a standard 14 x 14-inch roof vent opening in essentially the same manner as their RV counterparts. Both Furrion and Advent offer roof-mounted AC units that match the standard roof vent dimensions and are available in capacities of 13500 BTU and 15000 BTU. Roof-mounted acs possess additional features such as start capacitors, supplemental heat strips, and various distribution boxes designed to support ceiling assemblies found throughout the interior of the trailer. Since they were originally developed to withstand both vibration generated by mobile applications and harsh outdoor environmental conditions, RV-style roof-mounted AC units perform better than conventional residential units under similar conditions.
You’ll encounter numerous listings on horsetrailersworld.com containing trailers that feature RV-style roof-mounted ACs pre-installed. Utilizing pre-installed AC units greatly simplifies the process of installing an AC in your new trailer and enables you to evaluate the quality of the installed unit prior to making your final purchase decision.
For considerably lower initial expenses and ease-of-use for operating from generators (smaller generators), window-mounted portable air conditioners can be installed in sliding windows (custom panels are generally required to cover gaps created by the installation).
However, since these units produce substantially less cooling capability than roof-mounted units (typically 5,000 – 6,000 BTUs), they represent less desirable alternatives for full stall coverage in extremely hot climates. Additionally, mounting a window unit requires fabrication of custom components (in order to properly secure it in position), which adds additional expense to the overall cost of acquiring an AC unit.
More recent products offered by manufacturers such as Furrion (Chill He and Chill Cube series) employ variable speed compressors that adjust their output based upon current cooling requirements, versus turning on/off as traditional AC units do. By virtue of operation at varying speeds, these units produce reduced Noise levels while conserving energy during periods of minimal load requirements.
Generally more expensive than their predecessors, these newer units provide improved efficiency benefits, particularly relevant to owners concerned about excessive Noise generation related to their horses or requiring extended off-grid camping excursions.
Additionally, low-profile designs reduce height restrictions encountered at certain competitions and venues.
Fans are undervalued. Even with a full-function air conditioning system installed in your trailer, providing excellent air movement inside the trailer will undoubtedly enhance the comfort experienced by your horses. Evaporative coolers (“swamp” coolers) can be beneficial in drier climates but lose effectiveness as humidity levels rise. While evaporative coolers can be advantageous in reducing ambient temperatures in dry climates, they will not be effective in humid climates such as those found along the southeastern seaboard during peak summer months. In dry climates such as Arizona or New Mexico, they can assist in lowering temperatures without drawing heavy amounts of electrical power associated with compressor-based systems.
Typically, fans serve as supplements to AC systems by improving air flow at highway speeds with windows open or distributing cooled air when an AC is operational.
Cooling capacity. Choose an air conditioner that matches BTUs for your space and climate. Be conservative when selecting an air conditioner; it’s better to choose a slightly larger unit than a smaller unit.
Start capacitors & soft start kits. The single largest drain on a compressor-based AC occurs at startup. A start capacitor reduces this surge, allowing you to run your AC unit off a smaller generator. If you intend to run your AC off a generator, check whether the unit has been equipped with a capacitor or plan to spend money on an add-on soft-start kit.
Air distribution & thermostat functionality. Some units (such as the Advent Air) incorporate thermostats and fan speed controls into their design. Other units may require separate ceiling assemblies or control panels. Consider what functionality you require when selecting an air conditioner.
Heating strips or heat pumps. If you travel during shoulder season (fall/spring), heating strips allow you to use the same AC unit to provide heat. Note that most heating strips begin losing effectiveness around 35°f; therefore, they are useful during fall and spring but not as reliable substitutes for central heaters in cold weather.
Generator power consumption & efficiency. Typically, a 13,500 BTU AC will consume between 12 and 13 amps while operating. This factor becomes important when sizing your generator(s) for campsite electrical hook-ups as well as simultaneous use with other equipment (lights/refrigerator/etc).
Vibration & Noise levels. This characteristic pertains solely to equine concerns; excessive vibration/Noise generated by an AC unit may cause undue stress to your horses. Seek out units incorporating vibration-reducing brackets (some examples include Dometic’s bracket technology) and quieter blower motor designs.
Installation weight & complexity. Typical weight ranges for 13,500 BTU AC units range from 60-90 pounds. Mounting these units onto trailer rooftops typically necessitates assistance from another person; lighter units with foam housing instead of metal enclosures simplify rooftop installations. Numerous users comment that mounting their AC unit onto the roof was one of the greatest challenges faced during their entire installation process.
Durability & weather resistance. Units exposed outdoors must endure exposure to road grime, rain, and UV radiation from sunlight. Purchase units designed specifically for mobile applications that feature UV-resistant shroud materials, carbon steel base plates, and sealed electrical connectors.
You should expect to spend approximately $780-$1,600 for a quality 13,500 BTU roof-mounted AC unit. Most of the Dometic Brisk II models range in price from $900 to $950, depending on market availability. Similar units, such as the Advent Air model, also range within a similar price point. Units with variable speed fan control from Furrion sit at the upper end of the price spectrum.
Those prices reflect the cost of the unit alone. Installation costs will vary based on how easy it is to mount the unit on your roof. Roof mounting is relatively easy if your roof has been previously reinforced to carry the additional weight of a roof-mounted AC unit and all necessary electrical connections have been made prior to your installation.
If your roof has not been previously reinforced to carry the weight of a roof-mounted AC unit or if electrical connections were not made, a professional installation is advised, as adding these components can add hundreds of dollars to the overall installation cost.
Other costs you may encounter in addition to the unit cost include: roof sealant, bracing kits, heat strips, and a start capacitor (depending on the type of compressor). Add-on costs can be anywhere from $100 to $300.
Window-mounted AC units are less expensive than a roof-mounted unit. However, window-mounted units typically require additional customized panels, and although the initial purchase price is lower, the overall life expectancy of a window-mounted unit is usually lower than that of a roof-mounted unit, therefore offering less value when selling your trailer.
Roof-mounted units are typically more expensive due to the added cost of the unit itself. However, a roof-mounted unit uses less energy and saves money on generator fuel and electricity. Regardless of which option you choose, always consider purchasing a product with a multi-year warranty. Better manufacturers provide warranties that support their products for extended periods. When you are far from home with your horses in tow, having a quality product supported by a manufacturer is beneficial.
While a roof-mounted AC unit, such as a 13,500 BTU, uses approximately 1300 to 1700 watts while operating, the startup surge can reach upwards of 2800-3000 watts or more. Therefore, a 3000-watt generator is generally the minimum size for a roof-mounted AC unit. With sufficient “headroom” above the normal operating load, you will avoid burning out either the generator or the AC unit. A start capacitor or soft-start kit significantly decreases the startup surge and allows many owners of generators rated at 2000 watts to successfully operate a 13,500 BTU AC unit in mild weather conditions. One of the best upgrades you can perform to increase the efficiency of your system is by using a start capacitor or soft-start kit.
When performing your own installation of a roof-mounted AC unit, follow these steps before beginning:
One owner who installed an Advent Air model noted that his installation took approximately two hours with assistance from another individual and described it as “pretty straightforward” once he completed reinforcing the roof.
Professional installation of a roof-mounted AC unit is highly recommended for trailers that do not already have roofing bracing. Failure to reinforce the roof will ultimately lead to increased flexing of the roof structure, which will worsen over time and will likely create additional issues related to water entry into your trailer.
AC units can greatly extend their lifespan when properly maintained. Several areas you should maintain regularly include:
Air conditioning is just one component of providing comfort to your horses while towing them across country. Your horses remain comfortable while being hauled when you take advantage of good ventilation, adequate access to water, reasonable departure times during peak heat days, and regular rest stops.
Typical interior temperatures in relation to outdoor temperatures are considered acceptable when:
On extremely hot days (95 degrees+ temperature), even an efficient 13,500 BTU AC unit will find it difficult to achieve interior temperatures below 90 degrees without aid from other factors contributing to cooling your trailer interior space. Traveling during cooler parts of the day (early AM or late PM) and parking in shaded areas whenever possible will contribute positively toward lowering interior temperature.
Regardless of whether or not you have an AC unit installed in your trailer, traveling early in the morning or later in the evening is significant because interior temperatures tend to track ambient temperatures with some delay. As exterior temperatures rise, interior temperatures will eventually follow suit.
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