When installing a rear AC unit in a camper van, ensuring thorough insulation and sealing is crucial to maintain comfort and energy efficiency. Spray foam is highly effective for filling gaps and cavities around the AC unit, creating an airtight barrier that prevents drafts and heat exchange. In my experience, carefully applying spray foam in layers helps avoid expansion that could warp surfaces while still achieving a good seal. After the foam sets, using a high-quality caulk around seams and joints is essential to close any remaining gaps. I found that using a flexible, waterproof caulk works best as it can withstand the movements and vibrations from driving. Paying attention to corners and edges around the installation area guarantees no moisture or air leaks. Finally, applying a weather sealant over all treated areas adds an extra protective layer against water intrusion and weather damage. It’s important to choose sealants compatible with the surfaces of your van and the materials used in your installation. Once sealed properly, your camper van’s rear AC unit will be better protected against temperature fluctuations and harsh road conditions, improving comfort during your travels. Overall, taking the time to properly spray foam, caulk, and weather seal your AC installation can save you from costly repairs and improve the lifespan of your system. This approach helps maintain a cozy, well-insulated interior essential for a great van life experience.