Are Your Ducts Popping? Here’s Why.

Hearing strange sounds coming from your ducts can be more than just annoying. If your ducts are regularly popping or making other unusual sounds, it could indicate a more serious problem that an HVAC pro should investigate.

Your air conditioner is designed for air to flow smoothly through the ducts and into your home. If you’re hearing popping noises in the ducts every time your air conditioner goes through a cycle, something is amiss.

Here are some possible reasons your ducts may be popping:

Differences in pressure.

Differences in pressure between the supply and return ducts can cause a rumbling or popping sound as the ducts expand and contract and cause what’s known as ‘oil canning.’

Dampers on the supply side of your air ducts could also be closed, causing a pressure buildup that can cause a popping sound. A professional can check your system and make sure the dampers are open and air can flow freely.

Too many closed supply vents.

Too many of your supply vents may be closed, causing a pressure imbalance that makes a popping sound.

Your air conditioner is designed to work with all the vents open, so you should never have more than 10% of them closed when your A/C system is running.

If air hits a blocked vent, it’s pushed around to open vents, leading to uneven cooling and possibly strange sounds coming from your ducts.

Check that all vents in your home are open and free of dust and dirt.

Poorly sealed ducts.

Your ducts are an essential part of your HVAC system, and if they’re improperly sealed, they can leak air.

Poorly sealed ducts waste energy, increase the cost of cooling your home, and can accumulate debris inside them. They can also make popping sounds as air escapes and pressure imbalances occur.

Sagging or bent ductwork can also cause popping sounds, as air can’t flow as it should.

Ducts that sag, are bent, or aren’t well-sealed mean you’ll have to run your A/C longer to cool your home. If you hear noise from your ducts and there doesn’t seem to be enough cool air coming from your vents, it’s time to have your ducts inspected for leaks.

Your ducts may also not be large enough to accommodate your current HVAC system.  If your system pushes more air than your ducts can handle, you may hear popping or other sounds as air backs up.

The fan speed setting may also be too high, causing a popping sound. You can try lowering the fan speed, but you may find that some rooms in your home aren’t getting cool enough.

The shape of your ducts could also be a factor in how much noise they make. Circular ducts can generally handle more pressure and make less noise than square or rectangular ducts, which can expand and contract more easily.

A professional can inspect your HVAC system and your ducts to determine if their size or shape could be the problem or if your fan should be set at a different speed.

Dirty air filters.

Your air filters may be dirty and need changing.

Dirty air filters block the free flow of air and can cause sounds from your ducts as your system struggles to push air through a dirty or clogged filter.

Be proactive about changing filters regularly, as often as once a month in the summer months when our air conditioners run constantly.

Regularly changing the air filters is one of the simplest and most effective things you can do to help your HVAC system run smoothly.

Poor HVAC system maintenance.

Your HVAC system may need professional maintenance.  As hard as our air conditioners work in Arizona, neglecting maintenance will invariably lead to other, more costly problems.

If you haven’t maintained your system regularly, it’s probably not working at peak efficiency and may be making popping and other noises.

Chas Roberts has a 26-point maintenance checklist to keep your A/C system running in top shape. It includes:

  • Check refrigerant levels
  • Inspect disconnect switch
  • Clean condenser coil
  • Test safety controls
  • Lubricate all moving parts
  • And more

There’s no substitute for regular professional HVAC system maintenance, and neglecting it always ends up costing more in time, money, and aggravation.

Air conditioners also lose efficiency as they age.

If your air conditioner is more than ten years old and you’re thinking of replacing it with a new unit, a variable speed air conditioner that can run at lower speeds may reduce popping and other sounds coming from your ducts.

You’ll also see significant savings in energy costs with a variable speed A/C unit.

A Chas Roberts pro can help you choose a new, more efficient air conditioner that’s right for your home.

Water trapped inside your air conditioner.

Water trapped inside your air conditioner can cause a banging or popping sound. While we often go for months without much rain in Arizona, we do experience some heavy rainstorms.

Water and debris can enter your air conditioner and prevent it from working as it should. If you suspect this may be the problem, you can turn off the power to the unit and remove debris around the unit, but an HVAC pro should do any needed repairs.

Electrical problems.

Electrical problems could be causing the popping sounds.

You may have an electrical problem if you hear popping in the ducts and possibly a burning smell when your air conditioner runs. Loose wiring connections, wear and tear, and poor maintenance can all lead to electrical malfunctions.

For safety, professionals should always be called to address electrical problems.  Turn off the power at the main switch and call an HVAC pro.


While HVAC systems are never completely silent when they run, you should investigate regularly occurring popping sounds or other strange noises to ensure there isn’t a more serious problem with your system.

Air conditioner and duct repairs are not do-it-yourself projects and should be handled by a qualified HVAC professional.

Family-owned Chas Roberts is the largest and oldest residential HVAC company in Arizona. Contact us for affordable, quality service.