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  1. Central Air Conditioning Is Making a Sound and Blowing Cold Air

    June 22, 2012 by admin | Category: Educational, Helpful, InformationTags: , , | Comments (0)

    Many homes that experience long periods of heat benefit from central air conditioning, which blows cold air from vents throughout the house while making less noise than a traditional wall unit. Still, like most appliances, a central air unit can experience problems, including loud noises or sustained rattling either in the unit or the vents. Causes for these sounds range from innocuous to serious enough to warrant calling the repair man.

    1. Outdoor Fan Obstruction

      • While the interior of the house is largely under the homeowner’s control, the outdoors are home for a host of animals that use man-made shelters as readily as their natural counterparts. The main fan of the central air unit is located outside and may appear like a good shelter, with warm coils, plenty of access to air and coverage from aerial predators. Unfortunately, the large, spinning metal fan at the center of this unit spells doom for creatures looking for shelter from the sun or rain. When an animal dies in the fan, it can stop it from turning altogether or simply scratch the fan blade, causing a constant noise during operation.

      Ductwork Temperature Change

      • If the central air unit switches from hot air to cold air, or if the unit is just starting up after a long period of inactivity, the ductwork may expand suddenly, making a popping or even a small thunder noise. When the air conditioner is turned off, the ductwork can contract from lack of air pressure. When that pressure is renewed thanks to the main air fan, the vents will pop out suddenly.

      Mechanical Malfunction

      • Some mechanical problems with the air conditioning unit can also cause noises. In the case of the central air unit, a heat pump, compressor or condenser malfunction can create noises ranging from whining to vibrating to buzzing and even grinding. Each of these parts affect the flow of refrigerant during air conditioning, and, while a serious malfunction usually leads to a complete breakdown of the unit, intermittent problems may let the unit blow cold air while still causing the disturbing sounds. If your air conditioning unit makes these noises, shut it down and call an HVAC repair professional for service.


      • Dead animals are not the only possible sources of air conditioner sound and, if the sound is coming from inside and consists of small regular taps, infestation is a possible problem. Rats, mice and other infesting animals use ductwork as a means of getting from one part of the house to the other. This infestation can actually cause damage to the ducts since gnawing creatures cut holes in the ducts that serve as entry and exit points.

    For more information, visit eHow