AC Fan Not Spinning: Complete Troubleshooting Guide
Is your outdoor AC fan not working? Follow our step-by-step troubleshooting flowchart to diagnose the problem, understand fair repair costs, and determine if you can fix it yourself.
What It Means When Your AC Fan Stops Spinning
The outdoor condenser fan is responsible for pulling hot air away from your AC system's condenser coils. When it stops spinning, your air conditioner cannot release heat, and cooling performance drops to near zero. You will notice the indoor air stays warm, and the outdoor unit may feel extremely hot to the touch.
The good news: 65-75% of non-spinning fan issues are caused by a $25 capacitor that takes 20 minutes to replace. The bad news: dishonest contractors will diagnose this as a $2,000 motor failure or $10,000 system replacement. This guide ensures you know exactly what is wrong before spending a dime.
Understanding Your Symptoms
When your AC fan is not spinning, specific symptoms point to specific causes. Use this guide to narrow down your issue:
Bad Capacitor
Probability: 65-75% of all fan failures
Repair Cost:
$150-$400
Symptoms:
- •Fan humming but not spinning
- •Motor warm/hot to touch
- •Fan starts if manually pushed
- •Works intermittently
QUICK TEST:
With power ON, carefully push fan blade with a stick. If it starts spinning and keeps running, it is definitely the capacitor.
Failed Fan Motor
Probability: 15-25% of all fan failures
Repair Cost:
$400-$750
Symptoms:
- •Fan completely silent
- •No humming sound
- •Motor extremely hot
- •Burning smell
- •Fan does not spin even when pushed
QUICK TEST:
Replace capacitor first to rule it out. If new capacitor does not fix it, motor is bad.
Bad Contactor
Probability: 8-12% of all fan failures
Repair Cost:
$150-$350
Symptoms:
- •Both fan AND compressor silent
- •No humming from anything
- •Thermostat calling for cooling but nothing happens
- •Clicking sound from outdoor unit
QUICK TEST:
Listen carefully. If you hear clicking from outdoor unit but nothing starts, it is likely the contactor.
Debris Blockage
Probability: 5-10% of all fan failures
Repair Cost:
Free-$150
Symptoms:
- •Visible leaves/debris in unit
- •Fan struggles to spin
- •Grinding or scraping sounds
- •Fan stops after brief spinning
QUICK TEST:
Visual inspection. Look through grille for debris blocking fan blades.
Tripped Breaker / Power Issue
Probability: 3-5% of all fan failures
Repair Cost:
Free
Symptoms:
- •Everything silent
- •No lights or sounds from unit
- •Recent power surge or storm
QUICK TEST:
Check breaker panel for tripped breaker. Check outdoor disconnect switch is in ON position.
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Step-by-Step Troubleshooting Flowchart
Follow these diagnostic steps in order. Each step narrows down the cause until you have a definitive answer.
Is power on?
How to Check:
Check breaker panel and outdoor disconnect
IF YES:
Continue to Step 2
IF NO:
Turn on breaker/disconnect. If it trips again, electrical issue - call electrician.
Is compressor running?
How to Check:
Listen for low humming from large cylinder in unit
IF YES:
Contactor is good. Issue is fan-specific. Go to Step 3.
IF NO:
Both silent = contactor failure OR power issue. Test contactor with multimeter or call pro.
Is fan motor humming?
How to Check:
Put ear close to unit (safely). Listen for buzzing/humming.
IF YES:
Humming = motor trying to start = 90% chance bad capacitor. Go to Step 4.
IF NO:
Completely silent = Check Step 5.
Does fan start when manually pushed?
How to Check:
With power ON, push blade with insulated stick through grille
IF YES:
Starts and keeps running = 95% bad capacitor. Replace capacitor ($150-$400).
IF NO:
Still won't spin = Motor seized OR capacitor + motor both bad. Call pro.
Is there visible debris?
How to Check:
Look through top grille for leaves, sticks, or blockages
IF YES:
Clean debris. Power on and test. If still not spinning, continue to Step 6.
IF NO:
No debris = Go to Step 6.
Is capacitor swollen or domed?
How to Check:
Remove access panel. Look at cylindrical capacitor. Top should be flat.
IF YES:
Swollen/domed = failed capacitor. Replace immediately.
IF NO:
Looks normal but still not spinning = motor failure OR needs multimeter diagnosis. Call pro.
Special Case: AC Fan Humming But Not Turning
If your AC fan is humming but not turning, this is the most definitive symptom of a bad capacitor. The humming sound is the motor trying to start but lacking the electrical boost from the capacitor. This diagnosis is 90-95% certain.
Confirmation Test:
- 1. With power ON and fan humming, take a long insulated stick or wooden dowel
- 2. Carefully reach through the top grille and give the fan blade a gentle push
- 3. If the fan starts spinning and continues running, it is 100% the capacitor
- 4. Turn off power immediately (running on bad capacitor damages motor over time)
- 5. Replace capacitor before next use
Why the manual push test works: A capacitor provides the initial electrical jolt to overcome motor inertia. When you manually spin the blade, you are physically overcoming that inertia. The motor can then keep running on its own, but it will fail to start again the next time without a working capacitor.
Repair Cost & Time Comparison
Once you have identified the cause, here is what to expect for repair costs and timelines:
| Issue | DIY Cost | Pro Cost | Time | Urgency |
|---|---|---|---|---|
| Bad Capacitor | $15-$35 | $150-$400 | 20-30 min | Medium |
| Failed Motor | $150-$300 | $400-$750 | 2-3 hours | Medium |
| Bad Contactor | $25-$50 | $150-$350 | 30 min | Medium |
| Debris Cleaning | Free | $75-$150 | 15-30 min | Low |
| Tripped Breaker | Free | Free-$100 | 2 min | Immediate |
Can You Run AC with Fan Not Spinning?
NO. Do not run your AC if the outdoor fan is not spinning. Here is why:
- •Compressor overheating: Without fan airflow, the compressor will overheat and fail. A $600 fan motor issue becomes a $2,500 compressor replacement.
- •High pressure damage: Refrigerant pressure builds dangerously high without heat dissipation, potentially rupturing lines.
- •No cooling anyway: The system cannot release heat, so you are running the unit with zero cooling benefit while risking catastrophic damage.
Maximum safe runtime with non-spinning fan: 5-10 minutes MAX (for diagnostic purposes only)
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Learn DIYQuick Recap: AC Fan Not Spinning
When your outdoor AC fan is not working, start with the simplest fixes: check the breaker, look for debris, and test if the fan spins when manually pushed. If the fan is humming but not turning, it is almost always the capacitor – a $200-$400 repair that takes 30 minutes. Do not let a contractor sell you a $2,000 motor replacement without testing the capacitor first.
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