The three main types of RV air conditioners and how they differ

RV air conditioners fall into three categories based on where they mount and how they work: rooftop units, which sit on top of your RV and are the most common; through-wall units, which mount on the side of your RV and work best for smaller spaces; and portable units, which sit inside and vent through a window or duct. Rooftop units cool the largest area most efficiently but require professional installation and add weight high on your RV. Through-wall units take up interior wall space and are noisier but cost less upfront. Portable units are the cheapest option and require no permanent installation, but they consume more power and cool less effectively than fixed units.

The cooling capacity of any unit is measured in British Thermal Units, or BTU. A 13,500 BTU rooftop unit is standard for most travel trailers and smaller motorhomes. Larger RVs or those in hot climates may need 15,000 BTU or higher. Through-wall units typically range from 5,000 to 10,000 BTU. Portable units rarely exceed 10,000 BTU. The higher the BTU rating, the more power the unit draws from your RV's electrical system — a critical constraint if you're running on battery or a small generator.

Key Takeaways

  • Rooftop units cool the most space and run most efficiently but require professional installation and add weight to your RV's roof.
  • Through-wall and portable units cost less and need no roof work, but they draw more power per BTU and cool smaller areas.
  • A 13,500 BTU rooftop unit is standard for travel trailers; larger RVs or hot climates may need 15,000 BTU or more.
  • Your RV's electrical system must support the unit's amperage draw, which varies by type and cooling capacity.
  • Installation costs for rooftop units typically range from several hundred to over a thousand dollars, depending on your RV's construction.

Rooftop units: the standard choice for most RVs

Rooftop air conditioners dominate the RV market because they cool efficiently and don't consume interior living space. The most common brands are Dometic, Coleman, and Atwood. Dometic's Brisk II and Penguin series are widely installed on new RVs and sold as replacements. Coleman Mach units are popular on budget-conscious builds. Atwood units are less common but known for durability. All three offer models in 13,500 BTU and 15,000 BTU capacities, with some manufacturers offering 16,000 BTU or higher for large motorhomes.

Installation requires cutting an opening in your roof, running ductwork or plenum chambers inside, and wiring the unit to a dedicated 30-amp or 50-amp circuit depending on your RV's electrical service. If your RV already has a rooftop unit, replacement is straightforward — a technician removes the old unit and installs the new one in the same opening. If you're adding a unit to an RV that doesn't have one, the work is more involved and typically costs between $800 and $2,000 in labor alone, plus the unit itself. Some RV service centers charge by the hour; others quote a flat rate for the job.

Rooftop units run on 120-volt AC power when you're plugged into shore power or running a generator. They draw significant amperage — a 13,500 BTU unit typically draws 11 to 13 amps, and a 15,000 BTU unit draws 13 to 15 amps. This means you cannot run a rooftop air conditioner on battery power alone; you need either a generator or a campground hookup. Some newer RVs with large battery banks and inverters can run a unit briefly, but sustained cooling requires external power.

Through-wall units: a middle ground for smaller spaces

Through-wall air conditioners mount on the exterior wall of your RV, with the condenser outside and the evaporator and controls inside. They work well in small travel trailers, truck campers, and RV bedrooms where a rooftop unit is overkill. Popular models include the Dometic Penguin Ductless, which mounts through the wall without requiring roof penetration, and various window-style units made by LG, Frigidaire, and other appliance manufacturers that RV owners adapt for their needs.

Through-wall units typically range from 5,000 to 10,000 BTU and draw 5 to 10 amps at 120 volts. Installation is simpler than rooftop units — you cut a hole in the wall, slide the unit in, and seal around it. Many owners complete the job themselves in an afternoon. The trade-off is noise: through-wall units are louder than rooftop units because the compressor sits closer to your living space. They also take up wall space that could otherwise hold storage or windows, and they're less efficient at cooling large areas.

Portable units: lowest cost and easiest to move

Portable air conditioners sit inside your RV and vent hot air through a window, roof vent, or flexible duct. They range from 5,000 to 10,000 BTU and cost between $300 and $800. Brands like LG, Frigidaire, and Whynter make models that RV owners commonly use. The main advantage is simplicity: no installation, no roof penetration, and you can take the unit with you if you upgrade your RV.

The downsides are significant. Portable units consume interior space, are noisier than rooftop units, and are less efficient because they pull cool air from inside your RV and exhaust hot air outside, creating a pressure imbalance that draws warm air in through gaps and seams. They also draw 5 to 10 amps, which is comparable to through-wall units on a per-BTU basis, but they cool much smaller areas. A portable unit works well as a supplement to a rooftop unit in a large motorhome or as the sole cooling source in a small truck camper, but it's not practical as the primary cooler for a full-size travel trailer.

Electrical requirements and power draw

Every RV air conditioner requires 120-volt AC power and a dedicated circuit breaker. Rooftop units need either a 30-amp or 50-amp circuit depending on their BTU rating and the RV's electrical service. A 13,500 BTU unit typically requires a 30-amp circuit; a 15,000 BTU unit may require 50 amps. Through-wall and portable units usually work on a standard 15-amp or 20-amp household circuit.

Your RV's electrical panel has a fixed amperage capacity — most travel trailers have 30 amps total, and most motorhomes have 50 amps. A rooftop air conditioner alone can consume most or all of that capacity, leaving little for other appliances. This is why many RV owners run their air conditioner while parked at a campground with shore power, then switch to other appliances when boondocking or running on generator. If you plan to run multiple high-draw appliances at once — an air conditioner, water heater, and microwave, for example — you'll need either a larger electrical service or a generator with sufficient wattage.

Comparing installation costs and complexity

Installation costs vary widely based on your RV's construction, the unit you choose, and your location. A rooftop replacement on an existing unit typically costs $500 to $1,200 in labor. Adding a new rooftop unit to an RV that doesn't have one costs $1,000 to $2,500 or more because the technician must cut a roof opening, install ductwork, and run new electrical circuits. Through-wall units cost $300 to $800 to install professionally, or you can do it yourself if you're comfortable with basic tools. Portable units require no installation — you unbox them and plug them in.

If you're buying a used RV, inspect the existing air conditioner before purchase. Check whether it runs smoothly, cools evenly, and doesn't leak. A failing rooftop unit is expensive to replace, so factor that into your offer. If you're buying new, most RVs come with a rooftop unit already installed, so you're paying for it as part of the purchase price rather than as a separate upgrade.

Maintenance and lifespan

Rooftop units typically last 10 to 15 years with regular maintenance. The main tasks are cleaning or replacing the air filter every few months, checking the roof seal annually to prevent leaks, and having the refrigerant level checked by a technician if cooling performance drops. Dometic and Coleman units are easiest to service because parts and technicians are widely available. Atwood units are less common but still serviceable at most RV service centers.

Through-wall and portable units have shorter lifespans — typically 5 to 10 years — because they're designed for lighter duty. Maintenance is simpler: clean the filter regularly and may support the vent is clear. Portable units are especially prone to dust accumulation because they pull air from inside the RV.

Frequently Asked Questions

Can I run an RV air conditioner on battery power?

Not practically. A rooftop unit draws 11 to 15 amps at 120 volts, which requires either shore power or a generator. Some RVs with large lithium battery banks and inverters can run a unit for a short time, but sustained cooling depletes batteries quickly. Through-wall and portable units draw less power but still require external AC power to run.

What's the difference between a 13,500 and 15,000 BTU rooftop unit?

A 15,000 BTU unit cools faster and handles hot climates better, but it draws more power and costs more upfront. For most travel trailers in moderate climates, 13,500 BTU is sufficient. Choose 15,000 BTU if you're in the Southwest, have a large RV, or want faster cooling on hot days.

Do I need to replace my RV's electrical panel to add an air conditioner?

Not if your RV already has one. If you're adding a rooftop unit to an RV without one, the technician will run a new circuit from your existing panel. If your panel is full or undersized, you may need an upgrade, which adds cost. Discuss this with your RV service center before committing to installation.

Can I install a rooftop air conditioner myself?

Roof work and electrical wiring are best left to professionals. Mistakes can lead to roof leaks, electrical fires, or voided warranties. Through-wall and portable units are simpler and more suitable for DIY installation if you're comfortable with basic tools and following instructions.

What should I look for when buying a used RV with an air conditioner?

Run the unit and listen for unusual noises. Check that it cools evenly throughout the RV and doesn't leak water inside. Ask the seller how old the unit is and whether it's been serviced recently. A unit that's more than 10 years old may need replacement soon, which is a significant cost to factor into your offer.