What You Need to Know Before Buying a Camper Air Conditioner

A camper air conditioner works differently from a home unit because it runs on your camper's power system — either 120-volt shore power when plugged in, or your generator when you're off-grid. The three main types are rooftop units (the most common), window units, and portable units, each with different power demands and installation complexity. Before you buy anything, you need to know your camper's power capacity, roof strength, and whether you want cooling while driving or only when parked.

Most modern travel trailers and motorhomes come with a factory-installed rooftop air conditioner, but older campers often have none, and many owners want to upgrade to a larger or more efficient unit. The decision between replacing an existing unit and adding a second one depends on your power budget — running two rooftop units simultaneously can overload a standard 30-amp service.

Key Takeaways

  • Rooftop air conditioners are the standard for campers but require 120-volt shore power or a generator rated for at least 15 amps; window and portable units use less power but offer less cooling.
  • Your camper's electrical panel shows its total amperage capacity, and a typical rooftop unit draws 13 to 15 amps, leaving little room for other appliances on a 30-amp service.
  • Installation of a rooftop unit involves cutting a hole in the roof, running ductwork, and connecting to your electrical panel — a job most owners hire out rather than do themselves.
  • Window units and portable air conditioners are cheaper and easier to install but cool only one room and may not work well in campers with poor insulation.

Understanding Your Camper's Power System

Your camper's electrical service is either 30-amp or 50-amp, and this number determines how much power you can draw at once. A 30-amp service provides 3,600 watts total; a 50-amp service provides 12,000 watts. You can find your service rating on the breaker panel inside your camper, usually near the entrance or in a cabinet.

A rooftop air conditioner typically draws 13 to 15 amps when running, which on a 30-amp service leaves only 15 to 17 amps for everything else — your water heater, refrigerator, microwave, and lights combined. If you try to run the air conditioner and a high-power appliance at the same time, you'll trip the breaker. On a 50-amp service, a single rooftop unit uses only about 25 percent of your available power, giving you much more flexibility.

If your camper has a 30-amp service and you want air conditioning, your realistic options are a single rooftop unit (running nothing else power-hungry), a window unit, or a portable unit. If you have 50-amp service, you can run a rooftop unit and still use most other appliances normally.

Rooftop Air Conditioners: The Standard Option

A rooftop unit sits on top of your camper and cools the entire interior through ductwork. The most common brands are Dometic, Coleman, and Advent, and they range from 13,500 BTU (British Thermal Units) to 15,000 BTU for standard campers. BTU measures cooling power — higher numbers cool larger or hotter spaces faster, but they also draw more power and cost more to run.

Installation requires cutting a rectangular hole in your roof, installing a mounting bracket, running the unit's ductwork to your interior ceiling, and connecting the unit to a 120-volt circuit in your electrical panel. Most owners hire an RV technician for this work because it involves roof sealing (to prevent leaks) and electrical work. The labor cost typically ranges from $500 to $1,500 depending on your location and whether you're replacing an existing unit or adding a new one.

The advantage of a rooftop unit is that it cools your entire camper evenly and runs quietly. The disadvantage is that it only works when you're plugged into shore power or running a generator, so you cannot cool your camper while driving. Some newer motorhomes have rooftop units that run on 12-volt power while driving, but these are expensive and less common in travel trailers.

Window and Portable Air Conditioners: Lower Power, Lower Cost

A window air conditioner mounts in a camper window or wall opening and draws 5 to 8 amps — roughly half the power of a rooftop unit. Portable units sit on the floor and vent hot air through a hose to a window or exterior vent, using similar power. Both are cheaper to buy (typically $300 to $800) and require no professional installation.

The trade-off is that window and portable units cool only the room they're in, not your entire camper. In a small travel trailer, this might be acceptable; in a larger motorhome, you'll have hot spots. They also tend to be noisier than rooftop units and may not cool effectively if your camper has poor insulation or you're in very hot weather.

Window units work best in campers with windows you can modify or that have existing wall vents. Portable units are easier to move between campers if you own multiple rigs, but they take up floor space and require a clear path to a window or vent. Both types work on 120-volt shore power or a generator, just like rooftop units.

Calculating Whether Your Generator Can Handle It

If you plan to use your air conditioner off-grid, your generator must be large enough to start and run the unit. A rooftop air conditioner draws about 15 amps running, but it draws 25 to 30 amps for the first few seconds when the compressor starts. Your generator's rated wattage must be at least 1.5 times the unit's running wattage to handle this startup surge.

A typical 13,500 BTU rooftop unit uses about 1,500 watts running, so you need a generator rated for at least 2,250 watts to start it reliably. A 3,000-watt or larger generator is safer and gives you room to run other appliances while the air conditioner is on. Smaller generators (2,000 watts or less) can run a window or portable unit but will struggle with a rooftop unit.

Check your generator's nameplate for its continuous wattage rating, not its peak rating. The continuous rating is what matters for running appliances over time. If your generator is undersized, you'll either need to upgrade it or choose a lower-power cooling option.

Installation: What to Expect and When to Hire Help

Installing a rooftop air conditioner involves several steps: cutting a hole in the roof, installing the mounting bracket and sealing it against leaks, running ductwork from the unit to your interior ceiling vents, and wiring the unit to a dedicated 15-amp circuit in your electrical panel. Each step requires specific tools and knowledge, and mistakes — especially roof sealing — can lead to expensive water damage.

Most RV owners hire a technician for rooftop installation. The cost is $500 to $1,500 in labor, plus the unit itself ($800 to $2,000). If you're comfortable with basic carpentry and electrical work, you can do some of the interior ductwork yourself and hire a technician only for the roof work and electrical connection, which saves money but still requires professional informed for the most critical parts.

Window and portable units require no roof work. A window unit needs a mounting bracket and weatherstripping; a portable unit just needs to be placed near a window with its exhaust hose routed outside. Both can be installed in an hour or two without professional help.

Maintenance and Seasonal Considerations

All camper air conditioners need regular maintenance to run efficiently. Clean or replace the filter every month during heavy use — a clogged filter reduces cooling and wastes power. For rooftop units, check the roof seal annually and reseal if you see cracks or gaps. In winter, cover your rooftop unit with a protective shroud to prevent debris and ice damage.

Window and portable units should be cleaned inside and out before storage and checked for leaks around the seal. If you store your camper in a hot climate year-round, run your air conditioner at least once a month to keep the compressor lubricated and prevent seals from drying out.

Consider your climate and how you use your camper. If you camp mostly in mild weather or in shaded locations, a window unit might be enough. If you camp in the desert or South during summer, or if you camp full-time, a rooftop unit or dual cooling system is worth the investment.

Frequently Asked Questions

Can I add a second air conditioner to my camper?

Yes, but only if your electrical service can handle it. On a 50-amp service, you can run two rooftop units if each has its own dedicated circuit. On a 30-amp service, two units will overload your panel unless you upgrade to 50-amp service, which requires professional work. A rooftop unit plus a window unit is a more practical combination for 30-amp campers.

Will a rooftop air conditioner work while I'm driving?

Standard rooftop units only work when you're plugged into shore power or running a generator, so no. Some newer motorhomes have 12-volt rooftop units that run on engine power while driving, but these are expensive and rare in travel trailers. If cooling while driving is important to you, ask the RV dealer whether your specific model offers this option.

How much does it cost to run a camper air conditioner?

Running costs depend on your local electricity rates and how often you use it. A rooftop unit drawing 15 amps at 120 volts uses about 1,500 watts per hour. If shore power costs $0.15 per kilowatt-hour, running it continuously costs about $2.25 per day. Generator fuel costs are higher — typically $5 to $10 per day depending on fuel prices and generator efficiency.

What's the difference between BTU and cooling power?

BTU measures how much heat an air conditioner removes per hour. A 13,500 BTU unit removes 13,500 units of heat per hour; a 15,000 BTU unit removes more. For a small travel trailer (under 30 feet), 13,500 BTU is usually enough. For larger motorhomes or very hot climates, 15,000 BTU cools faster, but it also draws more power and costs more to buy and run.

Can I install a rooftop air conditioner myself?

You can do parts of it, but the roof work and electrical connection should be done by a professional. Mistakes in roof sealing lead to leaks that damage your camper's interior and structure. Electrical mistakes can cause fires or shock hazards. Hire a technician for these critical steps and do the interior ductwork yourself if you want to save money.