Why does my HVAC make a popping sound?

Author: Ms. Georgianna McClure  |  Last update: Thursday, December 4, 2025

When ducts are too small, it can create a buildup of pressure in the system, which results in a clicking or popping sound. These noises can occur when the heating or cooling unit turns on or off, and sometimes persist throughout the cycle of the HVAC system.

How do I stop my HVAC ducts from popping?

These are some simple ways you can stop ductwork noise:
  1. Clean or Replace the Filter. ...
  2. Clean the Ductwork. ...
  3. Adjust or Upgrade the Dampers. ...
  4. Insulate Your Ductwork. ...
  5. Check Your Furnace. ...
  6. Change the Blower. ...
  7. Install Ducts with an Insulated Liner.

Why does my furnace sound like popcorn popping?

The blower in newer furnaces is much stronger than older models, leading to the contracting and expanding of the ductwork attached to it. As the motor kicks on, you'll hear this popping as the metal ductwork expands to accommodate the strength of the blower.

Why is my vent making a popping sound?

From what you are describing, that's normal thermal expansion of the ducts. When the heat is on, they raise in temperature and grow slightly, shifting around. When the heat turns off, they cool and shrink, shifting around. All this shifting causes popping, but it's completely normal.

What does a bad HVAC sound like?

Rattling (Inside the House), Clanking or Banging

Like “thwapping,” these sounds could be related to the furnace's blower assembly or motor, and are likely due to something being either loose or broken. If you hear louder banging sounds when the blower is running, shut the system off until you can get help.

There is a popping Sound When My Furnace Comes On Or Is Running?

Why is my air conditioner making popping noises?

POPPING/CRACKLING

If your AC unit is making a popping noise, it could be as a result of ice forming, either because the temperature is set too low or because of water drainage issues. If water can reach some of the more sensitive areas of your system, it could cause lasting (and expensive) damage.

How do you know when your HVAC is going bad?

Worse odors, such as burning metal or melting plastic, are signs of a serious HVAC malfunction. These smells could indicate burned-out wire installation or motor. Turn your AC unit off immediately and call for a professional to evaluate the extent of repair required.

What is the knocking sound in my HVAC system?

The blower is the “fan” unit, and it's usually located indoors. If it's unbalanced it will create a banging or knocking noise as the fan spins. Other out-of-balance or loose parts. If the sound is more like a clanking, it could mean the compressor itself is loose, or parts inside the blower unit are hitting each other.

What causes the popping sound in exhaust?

If your engine is getting more fuel than it needs, a rich fuel to air ratio is the result. When your car has leftover fuel in the exhaust and the cylinders, that fuel explosively burns and creates a loud popping sound. Specifically, here we mean delayed timing, which causes the backfire.

Why am I hearing noises from my vent?

A whistling or roaring sound from a supply air vent could mean the vent has either too much air flowing through it or the volume damper inside the vent is partially closed restricting the normal airflow. Homeowners often close vents in empty rooms so they don't spend money to heat or cool unoccupied space.

What is the popping sound in my central heating system?

A bubbling or popping sound could either be a sign of low water pressure or, more seriously, kettling. The water pressure on your boiler should be set between one and two on the gauge.

Why is my HVAC clicking?

Think of the AC capacitors as batteries that store and release electrical energy to the compressor giving it the “juice” needed to start running your AC unit. When the capacitors or contactor is faulty, your outdoor AC unit will start to click. The clicking is either of these two components trying to start your unit.

Why does my furnace sound like it's backfiring?

Delayed ignition is when that gas isn't ignited immediately, allowing the gas to build up in the furnace. The gas keeps building until—BOOM—it reaches a flame and finally ignites, causing a small explosion in your furnace.

Why does my furnace make a popping sound?

Homeowners often notice a popping sound when the furnace begins a cycle. This is due to warm air that hits the cold metal of the ducts, which causes expansion and produces that noise.

Is it normal for ductwork to make noise?

HVAC air ducts are frequently comprised of metal which makes them prone to causing noise with even the most minor disturbances. This ductwork noise can be a source of frustration for homeowners when it's constant or excessively loud.

How do you unblock an HVAC vent?

How to Clean Air Vents
  1. Turn off the power to your HVAC system.
  2. Unscrew and remove the air duct covers. ...
  3. Use your vacuum to clean as much of the air vent as possible. ...
  4. Use the vacuum to clean the grills on the ceiling. ...
  5. Put all covers back and turn the power to your HVAC unit back on.

Why is my vent making a popping noise?

This phenomenon occurs as a result of the temperature changes in the ducts. As cool air passes through a warm duct, the metal of the duct contracts and makes a popping sound. Similarly, as warm air passes through a cool duct, the metal of the duct expands and creates a popping sound.

Is exhaust popping good or bad?

While some automotive enthusiasts will tune their vehicles to produce this popping sound in a (more) healthy and sustainable way for the motor and emissions equipment, the vast majority of the time it's something that should be avoided and addressed promptly when it happens.

What causes popping in a sound system?

Speakers almost always pop due to some kind of issue with the connection between the source and the speaker. Usually, this is something simple, like a not-fully plugged-in cable, a damaged cable, or a lot of dust or rust inside the connectors.

How to stop HVAC ducts from popping?

Here are two ways to solve the problem:
  1. Seal and insulate your ducts. Wrapping your ducts in insulation should solve your “cold winter morning” heating duct popping noise. ...
  2. Replace your ducts. Replacing your ducts is usually more cost effective than insulating them.

Is it normal for HVAC to make noise?

An HVAC system usually won't run loudly unless there's a problem. Your HVAC system, if there's a problem, may make several different noises. You may hear a buzzing noise, a popping sound, or even clanking. When your HVAC system is making unusual sounds, you should never ignore it.

How much does a compressor cost for an air conditioner?

On average, AC compressor costs range from $800 to $2,300, with most folks paying $1,200 for a new one. However, your price will vary depending on factors like the size and brand of your compressor. Before you schedule your replacement, read on to learn about all AC compressor cost factors.

What is the most common HVAC problem?

Poor airflow is one of the most common HVAC problems. Common culprits of poor airflow include clogged air filters, obstructed condenser units, blocked vents, thermostat issues, refrigerant leaks, and dirty coils.

What is the average life of a HVAC unit?

A heating or cooling system is a significant investment, and it only makes sense to get as much use out of it as possible. In general, most HVAC systems will last 15 to 25 years, but depending on the type of system and other contributing factors, that estimate can be highly variable.

How do I know when my HVAC needs replacing?

It may be time to call a professional contractor to help you make a change if:
  1. Your heat pump or air conditioner is more than 10 years old. ...
  2. Your furnace or boiler is more than 15 years old. ...
  3. Your equipment needs frequent repairs and your energy bills are going up. ...
  4. Some rooms in your home are too hot or too cold.

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