One of the most common air conditioning problems is improper operation. If your air conditioner is on, be sure to close your home’s windows and outside doors. For room air conditioners, isolate the room or a group of connected rooms as much as possible from the rest of your home. For a list of common air conditioner problems and what to look for, check out our Energy Saver 101 infographic on home cooling.

Other common problems with existing air conditioners result from faulty installation, poor service procedures, and inadequate maintenance. Improper installation of a central air conditioner can result in leaky ducts and low airflow. Many times, the refrigerant charge (the amount of refrigerant in the system) does not match the manufacturer’s specifications. If proper refrigerant charging is not performed during installation, the performance and efficiency of the unit is impaired. Unqualified service technicians often fail to find refrigerant charging problems or even worsen existing problems by adding refrigerant to a system that is already full. Learn what to ask for when hiring a technician to maintain your air conditioner.

Air conditioner manufacturers generally make rugged, high quality products. If your air conditioner fails, begin by checking any fuses or circuit breakers. Let the unit cool down for about five minutes before resetting any breakers. If a central air conditioner’s compressor stops on a hot day, the high-pressure limit switch may have tripped; reset it by pushing the button, located in the compressor’s access panel.

Refrigerant Leaks

If your air conditioner is low on refrigerant, either it was undercharged at installation or it leaks. If it leaks, simply adding refrigerant is not a solution. A trained technician should fix any leak, test the repair, and then charge the system with the correct amount of refrigerant. Remember that the performance and efficiency of your air conditioner is greatest when the refrigerant charge exactly matches the manufacturer’s specification, and is neither undercharged nor overcharged. Refrigerant leaks can also be harmful to the environment.

Inadequate Maintenance

If you allow filters and air conditioning coils to become dirty, the air conditioner will not work properly, and the compressor or fans are likely to fail prematurely.

Electric Control Failure

The compressor and fan controls can wear out, especially when the air conditioner turns on and off frequently, as is common when a system is oversized. Because corrosion of wire and terminals is also a problem in many systems, electrical connections and contacts should be checked during a professional service call.

Sensor Problems

Room air conditioners feature a thermostat sensor, located behind the control panel, which measures the temperature of air coming into the evaporative coil. If the sensor is knocked out of position, the air conditioner could cycle constantly or behave erratically. The sensor should be near the coil but not touching it; adjust its position by carefully bending the wire that holds it in place.

Drainage Problems

When it’s humid outside, check the condensate drain to make sure it isn’t clogged and is draining properly. Room air conditioners may not drain properly if not mounted level.