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Covenant Heating and Cooling Blog

The Sounds and Smells of an Air Conditioner in Need of Service


Prompt repair is the way to keep AC problems from getting worse, and to prevent a total breakdown. You certainly don’t want that to happen in Tennessee in July! So how can you watch out for AC issues and catch them right away? Well, the key is not to watch. Use your ears and your nose. Air conditioners in need of service often make strange noises and bad smells. Here are the details.

Strange Noises

  • Rattle: While this is probably a simple fix, such as getting a wobbling component back into place and securing it tightly down, you don’t want to put off repairs. A loose component can easily become a flying-free component, which hits and damages other parts of the system.
  • Whistle: As you know from whistling with your mouth, or from your tea kettle, a whistle is caused by air being forced through a small opening. This could mean a loose seal in your AC unit or damage to part of your ductwork. To keep the correct air pressure and avoid wasting energy, have it checked out by a qualified professional.
  • Buzz: Is it bees?! Probably not. (Though to be honest, it’s not impossible.) Chances are, it’s either a vibrating component that needs to be tightened, or it’s an electrical problem. Since electrical issues with your AC can cause serious hazards, it’s best to get air conditioning service in Nashville, TN right away.
  • Click: Your AC will probably click a little bit at the end of the cooling cycle, when it shuts down. But if the clicking happens throughout, it can indicate a problem. Again, this can be caused by an electrical issue, so don’t delay getting repairs.
  • Boom: At the start of the cycle, if the compressor booms or bangs, this is an issue called hard starting. It can be resolved with a hard-start kit, which provides extra electrical oomph through a capacitor, to help the compressor start more smoothly.
  • Bubble or Hiss: The refrigerant in your coils spends much of its time as a gas rather than a liquid, and if damage to the coils allows it to leak, it may hiss on its way out. Then, air (which should not be in the system) can bubble through the refrigerant when it is a liquid. Either sound means your coils need a thorough inspection.

Bad Smells

  • Mildew: This is a familiar one. Whether it’s in your ductwork or in the condensate pan of your AC unit, there is mold somewhere if you are smelling mildew. You need AC service or a duct cleaning, and a qualified HVAC technician can determine which it is.
  • Bacteria: This can produce a sour smell or a rotten-garbage smell. Again, the bacteria could be growing in your ductwork or your condensate pan. Either can provide a nice, moist place for strange little ecosystems of bacteria to grow. Get it checked out right away! You shouldn’t be breathing that.
  • Fire: Overheating components may smell like burning dust or melting plastic. An electrical fire can even smell like dead fish, because both cause ammonia to be released into the air. Any of these smells indicate a very hazardous problem! Shut down the system. Don’t use it again until it’s been repaired.

Covenant Heating and Cooling is your trusted resource for reliable AC service in Nashville, TN. We are “Dedicated to the Promise of Serving You!” Contact us today.

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