For renters, finding the right AC unit can feel like a project in itself. Having lived with this exact older model for nine years, there was no question that our 15-year-old Friedrich would be replaced by Friedrich itself, since no other brand comes close. For peace of mind, all Friedrich WallMaster units come with a two-year parts warranty. Older units tend to be less efficient and more prone to breakdowns, per guidance from Energy Star. How it Compares to Other In-Wall AC Units on the MarketThere are a few other brands that offer in-wall AC Units.