• Air conditioners are really a quite magical invention that may not get nearly the respect they deserve. This appliance is capable of taking very hot air, dehumidifying it and sending it throughout the house as cold air. Such a sophisticated system is bound to face certain problems, and you can help narrow down those problems by figuring out the right questions to ask.
  
  

Why Doesn't the A/C Kick on?

• If the air conditioning will not kick on, see whether someone has tampered with the thermostat and set it too high for the air conditioning to turn on when the room gets uncomfortably warm for you. If the thermostat is set correctly, go to the main service panel to inspect for a blown fuse or a tripped circuit breaker.
  
  

How Often Should I Change the Air Filter?

• With regular use, the air filters should be changed at least once every month or two. During the hottest parts of the year, when you are running the air conditioner continuously, you might want to change the filter every two weeks. Anything that obstructs airflow will decrease the efficiency of the air conditioner.
  
  

What Should I Do to Make the Outside Unit More Efficient?

• The outdoor unit is known as the condenser, and proper airflow into this part of the system is required to attain maximum performance from your central air conditioner. You should not plant anything so close to the condenser that it will affect airflow. Straighten out any bent fins you notice on the condenser. A rattling sound emanating from the outdoor unit is a sign that a foreign object has fallen through the grille and is being hit by the fan. Remove the foreign object, and replace the fan blade if it is bent rather than trying to straighten it.
  
  

Should I Buy an Evaporative Air Conditioner?

• An evaporative air conditioner is most efficient in dry climate conditions. The higher your average humidity reading, the less effective an evaporative system is. If you live in an area of high precipitation, buying an evaporative air conditioner is a bad idea. Poor performance in a dry climate indicates dirty coils or an inadequate supply and flow of water, according to the writers of "Ortho's Home Repair and Problem Solver."
  
  

Why Is My Window A/C Vibrating and Making Noise?

• A window air conditioning unit that begins making a vibrating sound may have come loose from its housing. Locate the screws that connect the housing to the air conditioning unit and tighten them. Another cause for a noisy window unit is that the fan motor bearings have become dry, which can be remedied by lubricating the motor with SAE 10 nondetergent oil.
  
  

Why Is My Window Unit Short Cycling?

• The cause of a window A/C unit turning on and off repeatedly during a short time frame may be related to an airflow problem. If the flow of air through the condenser is obstructed, it can result in the problem of short cycles. Fix the problem by locating and removing the obstruction of airflow. You should also clean the fins and straighten any fins that have become bent to improve efficiency and get the unit back to regular cycling.