While modern central air conditioners are quiet, they’re not silent. Some people describe the sound of the outdoor unit turning on similar to a plane launching. Indoors, you may even hear brief clicking and a whoosh. That’s perfectly normal. There is a wide range of other potential sounds that aren’t. Let’s have a look at those.
Loud Bang on Startup
If you hear a loud bang from the outside unit when it turns on, that can be a serious problem. Technicians refer to it as a hard start, and excessive vibration may accompany it. It suggests an issue with the condenser pump, and the electrical surge it creates can even trip the circuit braker. If it’s an older condenser, the unit may be failing. If it’s a newer unit and you’ve caught it early enough, the fix could be as simple as replacing a bad ball bearing. If it goes on long enough, it can cause even a relatively young condenser pump to fail.
Banging
If there’s ongoing banging from the outdoor unit, stop using the system right away, and call a repair technician. The condenser pump may already have damage, and the damage can worsen. Banging inside the home is a serious concern as well. It’s probably related to the blower. It could be a bolt, for instance, that came loose and made the fan unstable. As with outdoor banging, this is a sign to stop using the AC until you’ve had a technician service it.
Whistling
A whistling sound typically suggests an airflow restriction, which causes high pressure in the system. If it’s coming from the HVAC filter, the filter has clogged, and you’ll need to replace it with a new one. If it’s coming from your vents, you can try cleaning them. If that doesn’t work, it may indicate a blockage in the ducts themselves. If you can’t identify the issue and need to call in the pros, turn off the AC until they get there. The high pressure can cause wear and tear on the blower and other components.
Squealing
Squealing sounds are bad because they suggest high pressure or friction. It’s possible that the cause is an air blockage, but it would have to be severe. If the noise is originating indoors, it’s likely the blower. It could be a worn fan belt, a lack of lubricant or a faulty motor. If it’s coming from outside the home, it’s probably the condenser fan. In either case, stop using the system immediately.
Rattling
Rattling sounds will most likely come from either the blower or condenser fan. The sound means there’s a loose part or a foreign object in there. If it’s an inside sound, turn the system off, and call a technician. If it’s an outdoor sound, you can first check the outdoor unit. Leaves, branches and other debris can get in there and cause the noises.
Buzzing
Buzzing suggests an electrical issue. Stop using the system right away. The sound can come directly from wires or an electrical component. It can also be the condenser pump. The pump might be stuck or frozen over. Whatever it is, there’s the potential for an electrical fire.
Hissing
Hissing may indicate a refrigerant leak. When refrigerant leaks out, you usually can’t see it. You may smell it, which will be a sweet odor. If the refrigerant leak is major enough, you’ll likely be able to hear it. The hissing sounds comes from the gas escaping the line. Don’t keep running the system. It can cause major damage to the condenser and evaporator systems.
Popping
A popping sound usually comes from the ducts and not the AC itself. Expansion and contraction of the metal can cause this. It can also be because the ducts are old and not as stable as they once were. If the sound is fleeting, it’s usually not much cause for concern. If the sound is persistent or loud, schedule a video camera inspection of your ducts. You may need to repair mounting hardware or even replace a section of the ductwork.
Do You Need an AC Repair?
Affordable Service Solutions Heating & Air Conditioning has been repairing ACs in Richmond and throughout the surrounding areas since 2012. We’re on call for emergency repairs. Our technicians also repair, maintain and install boilers, furnaces, ductless mini-splits and air-source and geothermal heat pumps. Ask us about our indoor air quality solutions, too! We install and service whole-house air purification systems as well. Call us today or contact us online with questions or to schedule a consultation or service appointment.
