How Many Watts Does an RV AC Use? Solar Sizing Guide

Key Takeaways

• Standard 13500BTU and 15000BTU rooftop RV air conditioners draw 1400W to 1700W (12A to 15.3A) from a 115 VAC 60 Hz 1-phase power supply.
• Locked-rotor starting current peaks between 45A and 60A, requiring a soft-starter accessory to reduce inrush down to 16A to 20A for inverter operation.
• Air entering the air conditioner is cooled by 15 to 20 degrees; 80 degrees F return air results in 60 to 65 degrees F discharge air.
• Low voltage control circuits operate on 12 VDC at 1 amp or less, controlling 115 VAC compressor and fan relays from a wall thermostat.
• Before servicing ceiling plenum wiring or roof shroud assemblies, always de-energize circuits and disconnect 115 VAC power and 12 VDC battery supplies to prevent electrical shock hazards.

How Many Watts Does an RV AC Use?

Air conditioning is by far the largest single electrical load inside a travel trailer, fifth wheel, or motorhome. Off-grid RVers seeking to boondock comfortably without noisy generator run time must understand both the continuous running watts and the high locked-rotor compressor starting surge.

General Information: These air conditioners were designed to operate from a 115 VAC, 60 Hz, 1 phase power supply.

• 13500BTU Rooftop AC (Coleman-Mach Mach 3): Draws approximately 1400W to 1500W (12A to 13A at 115 VAC) in steady-state cooling mode.
• 15000BTU Rooftop AC (Coleman-Mach Mach 15): Draws approximately 1600W to 1700W (15.3A running current).
• Starting Inrush Surge: Without soft-start circuitry, the single-speed compressor draws 45A to 60A (3500W to 5000W) for 150 milliseconds upon startup.
• DC Control Load: These low voltage controllers are capable of operating both the roof top air conditioner and any furnace with a 12 VDC control circuit of 1 amp or less (continuous current).

To learn how RV generation coordinates with broader solar system design, explore our technical guides on how many solar panels you need to power a house and how much energy a solar panel produces.

Cooling Performance and Vehicle Heat Gain

Understanding air conditioner performance dynamics ensures proper expectations in hot weather:

• Delta T Temperature Drop: As a general rule, air entering the air conditioner will be cooled about 15 to 20 degrees, depending on the outside temperature and humidity conditions.
• Temperature Example: For example, if the air entering the return air grilles in the air conditioner is 80 degrees F, the air leaving the discharge grilles in the air conditioner will be 60 to 65 degrees F.
• Capacity vs Heat Gain: If the desired inside temperature (normally 80 degrees F) cannot be maintained, then the heat gain of the RV is too great for the capacity of the air conditioner.
• Solar Heat Mitigation: Parking the vehicle in a shaded area, keeping windows and doors shut and avoiding the use of heat producing appliances in the vehicle will help to reduce the heat gain.
• Insulation and Glazing: When possible, the addition of insulation and tinted glass (especially in uninsulated vans) should be considered.
• Supplemental Heat: Note: The optional Elect-A-Heat heating assembly is intended to take the chill out of the indoor air when the air is a few degrees too cool for comfort.

Protection Controls and Electrical Circuitry

Rooftop air conditioning systems incorporate mechanical and electrical safety controls:

• High Pressure Safety Switch: R410A roof top air conditioners high pressure switch lockout circuit: Air conditioners and heat pumps using R410A refrigerant utilize a factory installed high pressure switch safety circuit.
• Safety Lockout Behavior: Once the high pressure switch has tripped, this safety circuit will “lock out” the compressor, preventing it from trying to restart or run until the 115 VAC supply power has been turned off and then back on to reset the high pressure switch safety circuit.
• Low Voltage DC Controls: The relays contain 12 VDC coils (which may be energized by a wall mounted thermostat) with contacts that control the 115 VAC used to power the roof top unit.
• Freeze Protection Thermostat: When the temperature of the evaporator coil drops below 28 degrees F, the switch will open, stopping compressor operation. Compressor operation will resume once the evaporator warms to 55 degrees F.
• Supply Voltage Verification: Anytime an air conditioner is not operating properly, the power supply should be examined by a qualified technician to verify that the air conditioner is receiving the proper power supply.

Sizing Solar Panels and Battery Banks for an RV AC

Running a rooftop air conditioner off-grid requires a substantial inverter and battery infrastructure:

• Inverter Sizing & Soft-Starters: Without a soft-starter, starting an RV AC requires a 3000W to 4000W inverter to handle 50A locked-rotor surges. Installing an aftermarket soft-starter limits starting surge to 16A–20A, allowing a 3000W inverter (such as a Victron 3000W pure sine wave inverter or EcoFlow DELTA Pro) to start and run the AC smoothly.
• Battery Storage Capacity: Running an RV AC drawing 1500W for 4 hours requires 6000Wh (6 kWh) of electrical energy. In a 12V system, this translates to roughly 500Ah of LiFePO4 battery capacity. A 400Ah to 600Ah 12V lithium bank provides reliable daytime and evening cooling. Consult adding a battery storage system to existing solar for deep-cycle battery sizing details.
• Rooftop Solar Array Sizing: Recharging a 5 kWh daily air conditioning draw requires 800W to 1200W of rooftop solar panels operating in good direct sun for 5 to 6 peak hours.

Electrical Safety and Installation Warnings

Rooftop RV electrical systems combine 115 VAC mains power and 12 VDC battery circuits:

• Shock Hazard Precautions: Warning - Shock Hazard: To prevent the possibility of severe personal injury or equipment damage due to electrical shock, always be sure the electrical power to the appliance is disconnected during installation.
• Circuit Protection: The 115 VAC circuit must be protected by a dedicated 20-amp time-delay fuse or HACR circuit breaker.
• Wire Gauge Standards: Use minimum #12 AWG copper wire for branch circuits up to 25 feet, and #10 AWG copper conductors for lengths exceeding 50 feet to prevent excessive voltage drop during compressor starting.

Technician Consultation and Limitations

If your air conditioner compressor trips the high pressure switch repeatedly, the fan motor fails to spin, or refrigerant lines show oil stains, stop running the unit. The Coleman-Mach manuals do not provide field refrigerant recharging procedures or sealed hermetic compressor motor rebuilding instructions. Contact a certified RV technician or licensed HVAC professional to diagnose sealed refrigeration circuits, inspect run capacitors, and verify power supply voltage.