HVAC Making Strange Noises?
Unusual sounds from your AC or furnace usually indicate a problem. Here's what different noises mean.
⚠️ Important: Squealing, grinding, or banging noises often indicate imminent component failure. Address quickly.
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Check These First (DIY)
Before calling for service, try these quick troubleshooting steps.
Identify the noise location
Is it from indoor unit, outdoor unit, or ductwork? This narrows down the cause.
Note when noise occurs
At startup only? Continuously? During certain cycles? This helps diagnosis.
Check for loose panels
Rattling can be loose access panels or screws. Secure any loose panels.
Check air filter
Whistling often indicates dirty filter or blocked return. Replace filter.
Look for debris in outdoor unit
Sticks, leaves, or debris hitting fan blades cause rattling/clicking.
Tried everything above and still having issues?
Our technicians can diagnose the problem in about 30 minutes.
Schedule Service: (704) 821-3632Common Causes & Repair Costs
What might be wrong and what it typically costs to fix.
| Cause | Likelihood | Cost | DIY? |
|---|---|---|---|
Loose Panel or Screw Vibration loosens panels. Tighten screws and secure panels. | Very Common | Free | ✓ Yes |
Dirty/Clogged Filter Causes whistling from restricted airflow. | Very Common | $5-$30 | ✓ Yes |
Debris in Outdoor Unit Sticks or debris hitting fan blades. Clear after turning off power. | Common | Free | ✓ Yes |
Failing Blower Motor Bearings Squealing or grinding from indoor unit indicates worn bearings. | Common | $400-$900 | Pro |
Failing Condenser Fan Motor Squealing or grinding from outdoor unit. | Common | $300-$600 | Pro |
Loose or Damaged Fan Blade Clicking, scraping, or wobbling sounds. | Moderate | $100-$300 | Pro |
Bad Capacitor Humming without startup, or clicking. | Moderate | $200-$300 | Pro |
Compressor Issue Hard starting sounds, grinding, or loud humming. | Less Common | $1,500-$3,500 | Pro |
Ductwork Expansion Popping or banging from ducts as metal expands/contracts. | Common | $100-$400 | Pro |
Loose Panel or Screw
DIYVibration loosens panels. Tighten screws and secure panels.
Dirty/Clogged Filter
DIYCauses whistling from restricted airflow.
Debris in Outdoor Unit
DIYSticks or debris hitting fan blades. Clear after turning off power.
Failing Blower Motor Bearings
ProSquealing or grinding from indoor unit indicates worn bearings.
Failing Condenser Fan Motor
ProSquealing or grinding from outdoor unit.
Loose or Damaged Fan Blade
ProClicking, scraping, or wobbling sounds.
Bad Capacitor
ProHumming without startup, or clicking.
Compressor Issue
ProHard starting sounds, grinding, or loud humming.
Ductwork Expansion
ProPopping or banging from ducts as metal expands/contracts.
Diagnose by Symptom
Describe what you're experiencing to narrow down the cause.
"Squealing or screeching from indoor unit"
Likely cause: Blower motor bearing failure. Address quickly before motor fails completely.
"Grinding or metal-on-metal from outdoor unit"
Likely cause: Condenser fan motor bearings or blade hitting something.
"Banging at startup or shutdown"
Likely cause: Ductwork expansion (popping) or loose blower wheel (banging).
"Humming but unit won't start"
Likely cause: Failed capacitor—motor trying to start but can't.
"Clicking repeatedly from outdoor unit"
Likely cause: Relay/contactor trying to engage, or debris hitting fan.
"Whistling from vents"
Likely cause: Dirty filter, closed vents, or undersized ductwork.
"Rattling from indoor unit"
Likely cause: Loose panel, loose blower wheel, or debris in unit.
Our Repair Pricing
Upfront, honest pricing. No surprises.
$89
Diagnostic Fee
Waived with repair
$200-$800
Most Repairs
20-45 minutes
Response Time
30-50%
Less Than Big Co's
* Prices shown are typical ranges. Final price depends on specific diagnosis.
Serving the Charlotte Metro Area
Same-day emergency service available • Response in 20-45 minutes
Frequently Asked Questions
Why is my AC making a loud noise?
Different noises mean different things: Squealing = motor bearings (address quickly). Grinding = fan blade or motor issue. Humming = capacitor or compressor. Clicking = relay, contactor, or debris. Banging = loose component or compressor issue. Most AC noises indicate a component that needs attention before it fails completely.
Is it safe to run my AC if it's making noise?
It depends on the noise. Mild rattling or humming is usually OK short-term. However, grinding, squealing, or banging should be addressed immediately—these often precede component failure. Continuing to run can cause more damage and higher repair costs.
How much does it cost to fix a noisy HVAC?
Cost depends on the cause. Simple fixes (loose panel, debris): Free-$50. Blower motor: $400-$900. Capacitor: $200-$300. Condenser fan motor: $300-$600. Our $89 diagnostic identifies the issue.
Why does my furnace make a banging noise when it starts?
Banging at startup is usually delayed ignition—gas builds up then ignites all at once. This is potentially dangerous and should be fixed immediately. Can also be ductwork popping (metal expanding) which is less serious but still annoying. A technician can differentiate and fix both.
Related Troubleshooting Guides
Concerned About That Noise?
Let us diagnose it before it becomes a bigger problem. $89 diagnostic (waived with repair).
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