What causes an air conditioning system to rattle?

What causes an air conditioning system to rattle? It depends on where the rattling is.

If you here rattling inside your home, here are some probable causes…

  1. Out of balance blower wheel caused by uneven lint build up on the wheel. There is a certain amount of dirt/lint bypass regardless of the type of air filter that you use.
  2. Losing a balancing weight on the blower wheel, they are pressed on and can shake loose.
  3. Worn blower motor bearings. They are all sealed bearings for life, which means they don’t last as long as oil type motors
  4. Loose motor mounts.
  5. Loose air filter, it may have a missing retainer wire.
  6. Unsecured access panel, it may not be installed correctly, or it may be missing retainer clips or screws.

If you here rattling on the side of your house here are some likely causes…

  1. Out of balance fan blade caused by a missing balancing weight.
  2. Worn fan motor bearings.
  3. Loose motor mounts.
  4. The compressor is at the end of its useful life.
  5. Loose panels or screws, or missing screws also.
  6. Refrigeration tubing rubbing against a metal panel.

If you hear rattling on the roof it’s probably because…

  1. Any of the above if you have a combination unit.
  2. Missing or deteriorated vibration isolation mounts.
  3. Failure to install a flexible connector to isolate the air conditioner from the ductwork. (Lowest bidder)
  4. The unit was installed without spring isolators on roof/ceiling combo roof construction. (Lowest bidder)

Is it normal for an Air Conditioner to Rattle?

It is not normal for a newer air conditioner to rattle if it does, something is wrong.

Older AC Rattle Sounds

Older air conditioners tend to rattle because of age, just like an automobile. Unlike an automobile, they will never become a classic, just a headache.

Rattling noises could be due to simple or complicated causes in the air conditioner unit. When you hear rattling from the exterior of the AC unit this is probably due to a foreign object that fell into the vents, such as leaves, sticks, twigs, or other debris from the outside. Another type of rattle that may not be considered a major malfunction of the unit, is loose screws, bolts, and fasteners.

However, rattling may indicate a serious problem if it is coming from the compressor and this is commonly heard in old, depreciated, and overused air conditioning units where its function starts to deteriorate. Sometimes the unit makes a chattering sound that may damage the parts inside, specifically the compressor if the annoying sound is ignored and left untreated. Another cause of rattling is the loosening or misalignment of the fan, so it is best to have the loose screws inside the casing checked with clean condenser coils and regular maintenance of air filters. 

What Should I Do If My AC Rattles on Startup and Doesn’t Cool?

If your air conditioner rattles on start-up and does not cool, you would be wise to call for service and leave it off until help arrives. Small repairs can grow larger if the unit is left on and is not cooling, worst still, you have no choice but to replace it with a new one. So the earlier you know the problem, the better. 

Do not ignore these issues and seek assistance by a certified HVAC technician to fix it as soon as possible.

Looking for AC Repair Near Tucson, AZ?

If you’re experiencing trouble with your air conditioner our licensed and insured HVAC team will be more than happy to inspect your cooling unit and perform ac repair, or if needed immediately, emergency air conditioning repair. We’ll take the heat so you can stay cool!

Heatwave Air Conditioning and Heating
(520) 623-1855
3131 E 45th St, Tucson, AZ 85713

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