RV AC installation requires choosing between roof-mounted and portable units, understanding your power supply limits, and deciding whether to hire a professional or handle it yourself

Most RV owners install air conditioning in one of two ways: a roof-mounted unit that sits on top of the RV and vents cold air down through ducting, or a portable unit that sits inside and exhausts heat through a window or vent. Roof units are more common in larger RVs and provide better cooling but require cutting a hole in your roof and running electrical lines. Portable units avoid roof penetration but take up interior space and work best in smaller RVs or as a supplement to existing cooling.

Before you buy or install anything, you need to know your RV's electrical capacity. Most RVs run on either 30-amp or 50-amp shore power, and a typical roof AC unit draws 13 to 15 amps when running. If you're already running other appliances—water heater, microwave, furnace—you may not have enough amperage left. Portable units draw less (usually 8 to 12 amps) but still compete for power. Check your RV's electrical panel to see what you have available.

Key Takeaways

  • Roof-mounted AC units require cutting an opening in your RV roof, running power lines to the unit, and securing it with sealant; portable units avoid roof work but consume interior space and draw significant power.
  • Your RV's electrical system must have enough spare amperage for the AC unit to run without tripping breakers when other appliances are on.
  • Professional installation costs between $500 and $2,000 depending on unit type and RV layout; DIY installation is possible if you're comfortable with basic electrical work and roof sealing.
  • Roof units require regular maintenance including filter cleaning and checking the seal around the roof penetration to prevent leaks.
  • Some RVs have factory-installed AC units that can be repaired or replaced by following the manufacturer's documentation and electrical diagrams.

Roof-mounted AC installation: the most common approach

A roof-mounted unit sits in a frame on top of your RV and pulls warm air from inside, cools it, and returns it through ducting. The installation starts with marking and cutting a rectangular hole in your roof—typically 14 inches by 14 inches for standard units. You'll need a jigsaw or reciprocating saw, a drill, and a level to may support the frame sits flush. Once the opening is cut, you insert the mounting bracket, find it with bolts, and seal the edges with roof sealant (usually a polyurethane or butyl-based product) to prevent water leaks.

The electrical connection runs from your RV's main panel to a dedicated breaker, then through the wall or along the roof to the AC unit. Most roof units require 15-amp or 20-amp breakers depending on the model. You'll need to run 12-gauge or 10-gauge wire (the gauge depends on distance and amperage) in conduit to protect it from weather and damage. If you're not experienced with RV electrical systems, this is the step where hiring a professional makes the most sense—a bad connection can damage your RV's electrical system or create a fire hazard.

Once power is connected, the unit sits on the roof frame and bolts down. The ducting—usually flexible aluminum or plastic tubing—runs from the unit down through the interior to distribute cold air. Most RVs route this through the ceiling or along walls, and you'll need to find it with clips to prevent sagging. The final step is testing: turn on the unit, check that cold air flows, and verify that the breaker doesn't trip when the AC runs alongside other appliances.

Portable AC units: lower installation complexity, higher space cost

Portable units sit inside your RV and pull warm air from the cabin, cool it, and exhaust the heat outside through a vent, window, or roof opening. They're smaller than roof units and don't require roof penetration, making them attractive for RV owners who want to avoid cutting into their roof or who have limited electrical capacity. Most portable units are between 8,000 and 14,000 BTU and draw 8 to 12 amps.

Installation is straightforward: place the unit where you want it (usually near a window or existing vent), connect the exhaust hose to a vent opening, and plug it into a standard 120-volt outlet. Some models come with window kits that seal the gap between the hose and the window frame. The trade-off is that the unit occupies floor or counter space and is louder than a roof unit. Portable units also cool less efficiently because they're fighting against heat that's already inside the RV, whereas roof units prevent that heat from entering in the first place.

If you don't have an existing vent opening where you want to place the unit, you'll need to cut one—a smaller job than a roof unit but still requiring a hole saw and sealant. Some RV owners run the exhaust hose through a window or door opening instead, which avoids cutting but reduces the seal and lets some cooled air escape.

Electrical requirements and power management

Your RV's electrical system is the limiting factor for AC installation. A 30-amp RV has a total of 30 amps available across all circuits. A roof AC unit alone uses 13 to 15 amps, leaving only 15 to 17 amps for everything else—water heater, microwave, furnace, lights, and outlets. Running the AC and microwave at the same time will trip the main breaker. A 50-amp RV has 50 amps total, split between two 50-amp legs, giving you more headroom but still requiring careful management if you run multiple high-draw appliances.

Before installation, map out your current electrical load. Check your RV's electrical panel diagram (usually in the owner's manual or on the inside of the panel door) to see which circuits exist and what's connected to each one. If you're installing a new AC unit, you'll need a dedicated circuit—one that runs only to the AC unit and nothing else. This prevents the AC from competing with other appliances for power on the same breaker.

If your RV doesn't have enough spare amperage, you have three options: upgrade to a larger shore power connection (if your RV is capable and campgrounds support it), install a portable unit that draws less power, or use the AC only when other high-draw appliances are off. Some RV owners also install a generator to run the AC independently of shore power, though this adds cost and complexity.

Professional installation versus DIY

Professional RV technicians charge between $500 and $2,000 for roof AC installation, depending on your RV's layout, whether they need to run new electrical circuits, and local labor rates. This cost includes the unit itself (typically $400 to $1,200), labor, and materials like wire, conduit, and sealant. Portable unit installation is cheaper—usually $200 to $500—because there's less electrical work and no roof penetration.

DIY installation is possible if you're comfortable with basic carpentry, electrical work, and roof sealing. You'll need a jigsaw or reciprocating saw, a drill, a level, wire strippers, a crimper, a caulking gun, and basic hand tools. The biggest risks are electrical mistakes (which can damage your RV or create a fire hazard) and roof leaks (which can cause water damage and mold). If you've never worked with RV electrical systems or roof sealing, hiring a professional is worth the cost to avoid costly mistakes.

Many RV service centers and independent technicians offer installation. Get quotes from at least two shops, ask what's included (unit, labor, materials, testing), and check whether they warranty their work. Some shops also offer financing options if the upfront cost is a barrier.

Maintenance and troubleshooting after installation

Roof AC units require regular maintenance to keep them running efficiently. The filter should be cleaned or replaced every month during cooling season—a clogged filter reduces airflow and makes the unit work harder. The roof seal should be inspected twice a year (spring and fall) for cracks or gaps; if you see any, clean the area and reapply sealant. Over time, the sealant can crack from UV exposure and temperature changes, so plan to reseal every two to three years.

If your AC unit isn't cooling as well as it used to, the most common causes are a dirty filter, low refrigerant, or a clogged condenser coil. Clean or replace the filter first. If that doesn't help, the unit may need professional service to check refrigerant levels or clean the coil. Portable units are simpler—if they're not cooling, check that the exhaust hose is clear and that the unit isn't in direct sunlight (which makes it work harder).

If the AC trips your breaker every time you turn it on, you don't have enough electrical capacity. This is a power management problem, not an installation problem. You'll need to either reduce your load (turn off other appliances) or upgrade your electrical system. If the breaker trips only occasionally, the issue might be a loose connection or a failing breaker—have a technician inspect the electrical connections.

Factory-installed units and replacements

Many newer RVs come with AC units already installed. If your factory unit fails, you can replace it with the same model or upgrade to a newer, more efficient unit. Replacement is simpler than new installation because the roof opening, electrical circuit, and ducting are already in place. You'll remove the old unit, disconnect the power, and install the new one in the same location. Most replacements take a few hours and cost $800 to $1,500 including the new unit and labor.

Check your RV's warranty before replacing a factory unit yourself. Some warranties require that repairs be done by authorized dealers. If your unit is still under warranty, contact the dealer first—they may cover the replacement at no cost. If the warranty has expired, you can use any may have access to technician, though sticking with an RV-specific shop is safer than a general HVAC contractor unfamiliar with RV systems.

Frequently Asked Questions

How much does an RV AC unit cost?

Roof-mounted units typically cost $400 to $1,200 depending on BTU rating and brand. Portable units range from $300 to $800. Installation labor adds $500 to $2,000 for roof units and $200 to $500 for portable units. Total installed cost is usually $900 to $3,200 for a roof unit or $500 to $1,300 for a portable unit.

Can I install an AC unit in an older RV?

Yes, but older RVs may have limited electrical capacity or roof condition issues. Have a technician inspect your RV's electrical panel and roof before purchasing a unit. If your RV has a 30-amp system and limited spare capacity, a portable unit or a smaller roof unit may be your only option without upgrading your electrical system.

Will cutting a hole in my roof cause leaks?

Not if the installation is done correctly. The roof opening is sealed with polyurethane or butyl sealant, and the unit's flange sits over the opening to shed water. Leaks happen when the sealant cracks or wasn't applied properly. Inspect the seal twice a year and reseal every two to three years to prevent problems.

Can I run my AC on battery power alone?

No. AC units draw too much power for RV batteries to handle for more than a few minutes. You need either shore power (campground hookup) or a generator. A generator large enough to run an AC unit (usually 5,000 to 7,000 watts) is expensive and adds weight to your RV.

What size AC unit do I need?

This depends on your RV's size and insulation. A rough guide is 1 BTU per cubic foot of interior space, but most RVs use 13,500 to 15,000 BTU roof units or 8,000 to 14,000 BTU portable units. Ask your RV manufacturer or a technician for a recommendation based on your specific model.