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The demand for a used roof air conditioner for RVs has grown as travelers seek budget-friendly cooling solutions without sacrificing comfort. This guide explains how to evaluate, install, and maintain a pre-owned RV roof AC, with practical tips to maximize efficiency and safety. Readers will learn about model compatibility, electrical requirements, common pitfalls, and where to source reliable units.

Understanding The Basics Of RV Roof Air Conditioners

RV roof air conditioners are designed to cool small living spaces while running on a combination of electrical power sources. Most units are ducted or non-ducted and sit on the vehicle’s roof. When considering a used unit, it’s essential to verify BTU capacity, voltage, and compatibility with the RV’s electrical system. Common BTUs for travel trailers range from 13,500 to 15,000 BTU, while larger motorhomes may use 18,000 BTU or more. A unit’s efficiency is influenced by insulation, ductwork, and climate, so a higher BTU unit isn’t always the best choice in a well-insulated RV.

Key Factors When Choosing A Used Roof Air Conditioner For RV

• Model And Brand: Popular brands include Dometic, Coleman-Mach, and Atwood. These brands typically have abundant spare parts and support networks, which is critical for a used unit.
• BTU Rating: Select a rating appropriate for the RV size and climate. Overkill increases power draw; underpowered units struggle in hot conditions.
• Electrical Compatibility: Most RV ACs run on 120V AC, with some models offering 110V/115V options. Check the RV’s electrical capacity (amps) and shore power availability.
• Refrigerant And Seal Condition: A used unit should show no signs of refrigerant leaks. If possible, request documentation or verification of refrigerant charge and seal integrity.
• Water Ingress And Roof Suitability: Inspect the roof area for leaks, broken seals, and compatibility with a roof vent through which the unit will vent hot air.
• Installation Kit Availability: Ensure that mounting brackets, gasket kits, and electrical wiring harnesses are available or transferable.

Inspection Checklist Before Purchase

• Visual Exterior Check: Look for cracks, corrosion on the housing, and damaged mounting feet. Ensure the unit seals properly against the roof.
• Interior Inspection: Check the fan, blower motor, capacitor, and control board for wear or unusual noises.
• Electrical Test: If possible, run the unit on shore power to confirm cooling function and observe voltage draw with a multimeter.
• Leaking Refrigerant: Look for oily residue around service ports, which can indicate a leak. A refrigerant leak often requires professional repair.
• Support and Parts: Confirm that replacement parts and service manuals are accessible for the model you’re buying.

Installation Considerations And Potential Challenges

Installing a used roof air conditioner requires careful preparation. The process includes removing the old unit (if replacing), verifying the rooftop cutout, and ensuring the new unit aligns with mounting holes. Key steps include:

• Shut off all power to the RV, and disconnect from shore power before starting any work.
• Inspect the roof deck for damage and replace or repair any compromised decking or sealant around the cutout.
• Apply a high-quality roof sealant or gasket to create a watertight seal between the unit and the roof.
• Mount the unit using the provided brackets, ensuring the unit is level for optimal drainage.
• Connect electrical wiring according to the manufacturer’s wiring diagram, taking care to use appropriate fusing and grounding.
• Test the unit on shore power, then verify proper condensation drainage and airflow inside the RV.

Common installation challenges include roof penetration leaks, compatibility with existing ductwork, and space constraints within the ceiling cavity. If a unit’s footprint differs from the previous model, professional rework of the sealant and duct connections may be necessary.

Electrical And Power Considerations

For most RV roof air conditioners, the power source is 120V AC, typically using a dedicated 15- or 20-amp circuit. Some larger systems may draw more current, which can impact campground electrical hookups. Consider these points:

• Electrical Capacity: Confirm the RV’s shore power capability (amp rating) to prevent tripped breakers or electrical overloads.
• Power Management: Use a surge protector and a surge-suppressing device to protect the unit from voltage spikes.
• Startup Surge: Some AC units draw a higher current at startup. Ensure the circuit can handle brief surges without nuisance trips.
• Alternatives: In high-heat campsites, consider a fan-only mode as a backup or pair with portable AC units if needed.

Maintenance Tips To Prolong Life Of A Used RV Roof AC

• Regular Cleaning: Clean the filter and evaporator coils to maintain efficiency and airflow. Debris around the unit should be cleared to prevent overheating.
• Seal And Insulation: Periodically inspect roof seals around the unit and replace compromised weatherproofing to prevent leaks.
• Refrigerant Health: Have a certified technician check refrigerant levels if cooling performance declines or if there are visible leaks.
• Drainage: Ensure condensate lines are clear to avoid water damage inside the RV.

Cost Considerations And Where To Buy

Used RV roof air conditioners can be a cost-effective option, often ranging from $300 to $800 depending on BTU rating, brand, and condition. A higher price may reflect better insulation seals, a newer model, or included installation hardware. Reputable sources include RV parts dealers, salvage yards with RV equipment, and online marketplaces that offer seller reviews and return policies. When purchasing used, factor in potential labor costs for installation and any required repairs or refurbished components.

Common Unit Models And Compatibility

• Dometic series: DD/Duotherm and Penguin models are common in many RVs and provide robust aftermarket support.
• Coleman-Mach units: Known for easy installation in a wide range of RV roof profiles, widely available replacement parts.
• Atwood and other OEM brands: Often found in older RVs; ensure availability of service manuals.

Before purchasing, verify the unit’s compatibility with your RV’s roof opening, wiring harness, and control panel. A misfit can incur additional roof repairs and mounting hardware.

Safety Considerations

• Electrical Safety: Always disconnect shore power during installation and use proper fusing and grounding.
• Gas Appliances: If the RV has propane appliances nearby, ensure proper clearance and ventilation during installation.
• Waterproofing: Ensure the sealant is fully cured and the roof is watertight before using the unit in rain.

Frequently Asked Questions About Used Roof Air Conditioners For RV

1. Can I install a used roof AC myself? Yes, but it requires mechanical and electrical aptitude. Consider professional installation if unsure about seals, voltage, or mounting.
2. Is a used unit reliable? Reliability depends on prior usage, maintenance, and model. A well-inspected unit with good seals and a recent refrigerant charge can perform well.
3. What maintenance is mandatory? Cleaning coils, inspecting seals, and verifying refrigerant health are essential for optimal performance and longevity.

Bottom Line

A used roof air conditioner for an RV can deliver solid value when approached with a structured plan. Focus on model compatibility, thorough inspection, and careful installation. Weigh the cost against potential labor and parts needs, and prioritize reliability and safety to ensure comfortable camping experiences without unexpected interruptions.