The compressed refrigerant travels from the condenser to the evaporator, a heat exchanger, where heat is absorbed from the surrounding air. When you turn on the air conditioner blower this cooled air is transferred to the passenger cabin through the ducts. If the air recirculation switch is on, air will be pulled from inside the cabin making the system more efficient once the inside air is cool. Otherwise fresh air is pulled in from outside. A drain tube allows condensation from humidity in the air to drain from the evaporator. The drain often leaves a water puddle on the ground that may look like a leak, especially if the A/C has been running on a humid day. If the drain becomes clogged it should be cleaned by probing it with a long dull object. If left clogged, the water can eventually work its way out onto the interior floorboards.