In this episode, our resident expert, Dan Danowski, explains what an air conditioner actually is and how it works. Video script: Welcome to Ask the Expert. I'm your expert, Dan Danowski. I'm here to answer your most pressing heating and air conditioning and ventilation-related questions. I'm a Sagittarius and I like Chicago-style hotdogs. Okay, let's get to the questions. This one's from Todd in Akron, Ohio. "Hey Dan, you're great." Thanks, Todd. "I love my air conditioner, but what is an air conditioner?" Okay, good question, Todd. An air conditioner is a very simple device actually invented for dehumidification, but it also cools too, which I'm sure you found out in those hot Akron summers. Full disclosure: I have no idea about the temperature in Akron, Ohio. You've got two big parts. You've got the condenser, which is outside, and you've got your evaporator, which is inside. The evaporator sends the refrigerant through those coils. Those are a coil network. Those two things pass the refrigerant back and forth and that takes the heat out of the air and dumps the heat outside. So, now when it goes back through, it's cooler. You blow air over that, you're going to get cool air in your house because dehumidified air carries less heat. That's science. If you run it backwards, that's what we call a heat pump. For more questions for Dan, ask in the comments below or on Facebook, or Twitter.