RV air conditioning falls into three main types, each with different power needs and installation complexity
An RV air conditioner is a rooftop unit, a portable unit, or a built-in system that cools the interior of a recreational vehicle. The three common types are rooftop units (mounted on top of the RV, requiring 13,500 to 15,000 BTU for most travel trailers), portable window units (sitting inside and venting through a window, typically 5,000 to 10,000 BTU), and ducted systems (integrated into the RV's existing ductwork, usually found in larger Class A motorhomes). Each type draws power differently: rooftop units need 30-amp or 50-amp shore power; portable units run on standard 15-amp household outlets; and ducted systems require the RV's onboard generator or shore power connection.
The choice between them depends on your RV size, how often you use it, whether you have reliable shore power access, and your budget. A travel trailer or Class B van typically uses a rooftop unit. A small camper van or someone who camps off-grid might choose a portable unit. A large Class A motorhome often has a ducted system already installed. Understanding what each type requires helps you avoid buying a unit your RV cannot power or support.
Key Takeaways
- Rooftop units are the most common RV air conditioner and require 30-amp or 50-amp shore power, making them impractical for boondocking without a generator.
- Portable window units cost less upfront and run on standard 15-amp power, but cool smaller spaces and take up interior room.
- Installation of a rooftop unit requires cutting a hole in the RV roof and running electrical connections, a job most owners hire a technician to perform.
- BTU rating (British Thermal Units) determines cooling capacity; most travel trailers need 13,500 to 15,000 BTU, while larger RVs may need two units or 20,000+ BTU.
- RV air conditioners draw significant power, so you need to know your RV's electrical capacity before purchasing to avoid overloading the system.
Understanding BTU ratings and how they match your RV size
BTU stands for British Thermal Units, a measure of how much heat an air conditioner can remove per hour. A larger RV needs a higher BTU rating to cool effectively. Travel trailers and Class B vans typically need 13,500 to 15,000 BTU. Class C motorhomes and larger travel trailers may need 15,000 to 20,000 BTU. A Class A motorhome often has two rooftop units, each 15,000 BTU or higher, or a ducted system with multiple zones.
Undersizing the unit means it runs constantly and never reaches your target temperature. Oversizing wastes power and money. A rough guide: multiply your RV's interior square footage by 1 BTU per square foot, then add 25 percent for hot climates or poor insulation. A 300-square-foot travel trailer in a hot climate would need roughly 375 BTU, so a 13,500 or 15,000 BTU unit is appropriate. If you are unsure, check your RV's original specifications or ask a dealer what the manufacturer installed. This calculation prevents you from buying a unit that will either run constantly or waste electricity.
Power requirements and whether your RV's electrical system can handle it
Rooftop air conditioners draw substantial current. A 13,500 BTU rooftop unit typically draws 11 to 13 amps at 120 volts. A 15,000 BTU unit draws 12 to 15 amps. This means you need at least a 30-amp shore power connection to run one unit safely, and a 50-amp connection if you want to run the air conditioner plus other appliances (water heater, microwave, other outlets) at the same time. Most campgrounds offer both 30-amp and 50-amp pedestals, but not all sites have 50-amp available.
If you have only a 15-amp outlet at a campground, a portable window unit rated for 5,000 to 8,000 BTU is your only option. Running a rooftop unit on a 15-amp circuit will trip the breaker repeatedly and can damage the unit or the RV's electrical panel. If you plan to boondock (camp without shore power), you will need either a portable unit or a generator large enough to power the rooftop unit—typically a 5,000 to 7,000-watt generator for a single 13,500 BTU unit. Knowing your RV's electrical capacity before you buy prevents costly mistakes and limits where you can camp.
Installation: rooftop units versus portable units
Installing a rooftop unit requires cutting a rectangular hole in the RV roof, sealing it against leaks, running 30-amp or 50-amp electrical wire from the breaker panel to the roof, and securing the unit with brackets and sealant. Most RV owners hire a technician at an RV service center to do this work, which typically costs $500 to $1,500 in labor alone, plus the cost of the unit itself ($800 to $2,000). The job takes one to two days. Poor installation can lead to roof leaks that damage the RV's interior, so hiring a professional is usually worth the cost.
A portable window unit requires no permanent installation. You set it in a window, seal the gap with foam or a sliding panel, plug it into a standard outlet, and you are done. Setup takes 15 minutes. The trade-off is that it occupies window space, reduces visibility, and cools only the when ready area around it. Portable units are best for small RVs or as a backup to an existing rooftop unit. Some RV owners use a portable unit during shoulder seasons (spring and fall) when cooling needs are lower, then install a rooftop unit for summer travel.
Maintenance and common problems to watch for
Rooftop units need regular maintenance to run efficiently. Clean or replace the air filter every month during heavy use, or every three months during light use. A clogged filter reduces cooling and forces the unit to work harder. Check the roof seal around the unit twice a year, especially after travel, to catch leaks early. Water inside the RV around the air conditioner is a sign the seal has failed. Addressing a small leak when ready prevents water damage to insulation and structural components.
The most common failure is a refrigerant leak, which reduces cooling capacity. If the unit runs but does not cool, or if you hear hissing sounds, the refrigerant may be low. Recharging refrigerant requires a technician and typically costs $200 to $400. Another frequent issue is a frozen evaporator coil, which happens when the unit runs in very cold weather or when airflow is blocked. If the unit stops cooling and ice forms inside, turn it off and let it thaw for several hours before restarting. These problems are easier and cheaper to fix if caught early.
Comparing rooftop, portable, and ducted systems
| Type | Power Needed | BTU Range | Installation Cost | Best For |
|---|---|---|---|---|
| Rooftop Unit | 30-amp or 50-amp shore power | 13,500–20,000 | $1,300–$3,500 | Travel trailers, Class B and C motorhomes |
| Portable Window Unit | 15-amp standard outlet | 5,000–10,000 | $300–$800 | Small RVs, boondocking, backup cooling |
| Ducted System | 50-amp shore power or generator | 20,000+ (multiple zones) | $3,000–$6,000+ | Large Class A motorhomes, full-time living |
Rooftop units offer the best balance of cooling power and efficiency for most RVs. They are quieter than portable units and do not take up interior space. The downside is the upfront cost and the need for shore power. Portable units are cheaper and work anywhere you have a standard outlet, but they are louder and less powerful. Ducted systems provide the most comfort for large RVs and full-time living, but they are expensive and usually come pre-installed on new motorhomes.
Your choice depends on how you use your RV. If you camp mostly at established campgrounds with shore power, a rooftop unit is the standard choice. If you boondock frequently or want flexibility, a portable unit may suit you better. If you own a large motorhome and spend months at a time on the road, a ducted system offers the most even cooling and comfort, though you will pay more upfront.
Frequently Asked Questions
Can I run an RV air conditioner on battery power alone?
No. A rooftop unit draws too much current for an RV's battery bank to supply for more than a few minutes. You need shore power (30-amp or 50-amp) or a generator. A portable window unit can run on a standard 15-amp outlet, which some RVs can power from their battery system for a short time, but this will drain the battery quickly.
What is the difference between a 30-amp and 50-amp RV connection?
A 30-amp connection supplies 120 volts at 30 amps, enough for one air conditioner and basic appliances. A 50-amp connection supplies 240 volts (two 120-volt legs at 50 amps each), allowing you to run an air conditioner, water heater, and other appliances simultaneously without overloading the system. Most travel trailers use 30-amp; larger motorhomes use 50-amp.
How much does it cost to replace an RV air conditioner?
A new rooftop unit costs $800 to $2,000 depending on BTU and brand. Installation labor adds $500 to $1,500. A portable unit costs $300 to $800 with no installation cost. If your existing unit is under warranty, the manufacturer may cover replacement; check your documentation or contact the unit's maker.
Will an RV air conditioner work while driving?
No. Rooftop units are designed to run only when the RV is parked and connected to shore power. Running one while driving would drain the battery and risk electrical damage. Some RVs have a separate dash air conditioner (part of the cab's HVAC system) that works while driving, but the living area air conditioner does not.
How do I know if my RV roof can support a rooftop air conditioner?
Most travel trailers and motorhomes are built to support a rooftop unit, but older or lightweight RVs may have structural concerns. Check your RV's manual or contact the manufacturer. A technician at an RV service center can inspect the roof and tell you whether it is safe to install a unit before you buy one.