The first thing (but not the most obvious thing) to check for is the fan unit inside your air conditioning. The clicking noise could be an obstructed or slightly bent fan blade hitting something inside the air handler repeatedly. Fan problems usually occur as a result of wear and tear or a lack of proper maintenance.

In short, the answer is no, air conditioners do not bring in fresh outside air. Rather, it takes the air inside your house and puts it through a heat exchange process. So, how exactly does it work? Generally, air conditioners move unwanted heat out of your home, thus lowering the temperature inside your home.

Does air conditioning heat as well as cool? This depends on the particular unit you have installed in your home. If your AC is also designed to work as a heat pump, then you can use your existing unit to heat your space too. If you've got an HVAC system, this also indicates that your aircon has a heating ability.