If you hear strange noises in your home, like hissing or popping, it’s probably not a ghost. It’s probably your HVAC system. But don’t worry, Schwantes is here to help. Learn more about common HVAC noises, the possible causes, and how to handle them.
What Is Making Noise?
Before we get into the different signs, knowing what part of your HVAC system is causing the noise is helpful. It could be a:
- Furnace
- Boiler
- Heat pump
- Air conditioner
- Air conditioner compressor
- Ductwork
- Thermostat
It’s okay if you’re unsure what part of your system is noisy. But if you can figure it out, that’s a great first step to remedying the problem.
11 HVAC Noises and What They Might Mean
Hissing
Hissing is one of the most common noises and often comes from your AC compressor or furnace. It could mean your compressor has a refrigerant leak or high internal pressure. If it’s loud and consistent, disconnect the AC power and call us. If it’s your furnace, it’s most likely a leaky air duct.
Popping
A soft or loud popping sound likely indicates an issue with your ductwork. It’s extremely common when you turn the heat on for the first time in a while. The popping sound is the cold metal expanding from the heat, which is normal and nothing to worry about. If it’s not from your heating system, you should schedule an appointment with a technician.
Buzzing
A buzzing noise from your air conditioning unit is usually a compressor malfunction, but it could also be a refrigerant leak or a loose part. None of these are particularly dangerous, but they can harm your AC unit if left unaddressed.
Booming
We know a booming sound can be very concerning. It usually means your furnace is trying to relight itself from the pilot light or an electric ignition. When you hear the booming, it typically means the furnace is unsuccessful. This can be dangerous, as the gas will build up and could be ignited all at once. The best solution is usually a professional cleaning of your furnace and flue.
Thwapping
If you hear that sort of echoey “thwap, thwap, thwap” sound, it could be something wrong with your blower’s fan blades. Check if you’re having airflow issues or if you can feel the air coming from your system. If you cannot, it’s likely a problem with the blades. Fix it as soon as possible because this issue causes unnecessary wear and tear on the system.
Clicking
Clicking is a very common (and very annoying) sound. And it could be coming from several places. If it’s from your AC unit, it could be a malfunctioning inside air handler, electrical components, or your thermostat. When the source is the furnace, this could be a good sign! The system may make this sound at the start of the season as it wakes up for the first time in several months. It just means it’s working!
Squealing or Screeching
On the other hand, squealing or screeching is a bad sign. It could mean a broken fan belt on your blower or a dry motor in need of lubricant. Pinpointing the source of this awful sound is difficult, so it’s best to call a professional when you hear this type of sound.
Clanking or Banging
Clanking and banging sounds dangerous but are usually just a loose or broken part. Typically, it’s not a serious hazard. However, it does require professional attention. Turn the system off if the clanking or banging gets louder or worse over time. The faulty part could be causing severe damage that will cost you more to fix.
Whistling or Screaming
If you hear high-pitched whistling or screaming — which can sound quite terrifying — you should shut off your HVAC system immediately. This type of sound acts as a warning that there’s something seriously wrong with your AC compressor or refrigerant pressure or there’s an internal leak in your AC unit. All of the above are bad news, so call a professional technician as soon as you can.
Rattling From Outside
If you hear rattling when standing outside your house, the sound is likely from your compressor. The clutch could be worn out, or the whole compressor could be failing. Another possibility is that one of the system’s pulleys has overused bearings. It’s hard to know the issue until you open up the system and inspect it.
Rattling From Inside
A rattling heard from inside your house is a little more concerning. It indicates a problem with your furnace blower or motor. It’s best to shut the system down until you can have a professional look at it. It’s similar to the problems associated with clanking and banging noises.
Enjoy Some Peace and Quiet
If your HVAC system is making funky noises, don’t wait to see if they go away — because they probably won’t. Call Schwantes, and we’ll send a technician out as soon as possible to assess the issue and get your HVAC back up and running without the scary noises.
When in doubt, shut off the system and reach out to us ASAP so your home can be calm and quiet again.
