When replacing the outdoor unit, should the indoor unit also be replaced?Of course we advise you to also replace your indoor system, but this is why: All outdoor cooling systems have a matching indoor unit that they are designed to work with to ensure efficient performance. When they aren’t paired with the other piece as a complete system, efficiency might suffer. As with many products, advancements have brought about newer, more efficient ways of doing things. Heating and cooling systems are no different. These developments most importantly include improved heating and cooling efficiency, but also include improved air handling, filtering and noise pollution reduction to name a few. Heating and cooling systems that are more than 10-15 years old usually need to be replaced. Not only do they feature outdated technology, but they are also less efficient than today’s models. Buying a new indoor unit at the same time means you’ll have a matched system to provide you with better comfort and efficiency for years to come.