What a glorious system a heat pump is. It cools your home like an air conditioner. It provides heating, and it does so incredibly efficiently. In a warm climate, it might even provide all the heat you need at an impressively low cost. And it can automatically and effortlessly switch between heating and cooling modes. How does one system manage all this? Your heat pump has a specialized component called the reversing valve. Here’s what you should know about how it works and what to do if it isn’t working.