Evaporator coils contain the system’s refrigerant as it converts from liquid to gas. The refrigerant moves through an expansion valve and into the evaporator coils. The liquid refrigerant moves through an expansion valve decreases pressure on the liquid refrigerant thus reducing by absorbing heat from the evaporator coil. Heat transfer occurs in these coils, creating a cold surface. The blower moves air across the cold surface, creating the conditioned air that cools your home. The gaseous refrigerant moves to the outdoor unit.