AC Fan Not Spinning

If the outdoor AC unit hums but the fan does not spin, the most common cause is a failed run capacitor, which costs about $120 to $400 to replace. Other causes are a bad contactor, a worn fan motor or a tripped breaker. Turn the system off quickly: running without the fan can overheat the compressor.

Typical pro cost

$120 to $700

LowHigh

Urgency: Fix today
DIY difficulty: Hard
Time to fix: 30 minutes to 2 hours (pro)
Prices: US typical range

Last reviewed October 2026

Central AC: what can go wrong diagram — Central AC: what can go wrong. Tap to enlarge.

Signs it's this problem

The outdoor unit hums but the fan blades do not turn
The fan spins slowly or only after a push
Warm air from the vents
The unit shuts off after a few minutes
A burning smell near the outdoor unit

Common causes

Bad capacitor

The capacitor gives the fan motor its starting kick. A bulging or weak capacitor is the top cause.

Failed fan motor

Worn bearings or an overheated motor stop the fan even with a good capacitor.

Stuck contactor

If the contactor does not pull in, neither the fan nor the compressor runs.

Tripped breaker or disconnect

Check the breaker and the pull-out disconnect near the unit.

Debris or bent blades

Sticks or a bent blade can block the fan.

How to fix it, step by step

1
Set the thermostat to off to protect the compressor.
2
Check the AC breaker in the panel and the disconnect box next to the outdoor unit.
3
With the power off at the disconnect, look through the top grille for sticks or debris blocking the blades.
4
If safe and the power is off, try turning the blades by hand with a long stick. Stiff blades point to a bad motor.
5
A tech can test the capacitor and contactor. A bulging capacitor top is a clear sign.
6
Replace the capacitor or motor, then run the system and check that the fan and compressor both start.

Safety: Capacitors store a dangerous charge even with the power off. Do not touch them unless you are trained to discharge them safely.

Tools and materials

Long stick or screwdriver handle
Flashlight

Approximate DIY cost: $20 to $60 for a capacitor (trained DIYers only)

Call a pro when

Any capacitor or contactor work
The fan motor needs replacing
The breaker trips again

AC Fan Not Spinning cost

Typical US price ranges for professional work, including labor and materials
Job	Typical cost
Run or start capacitor, installed	$120–$400
Contactor replacement	$150–$400
Condenser fan motor replacement	$300–$700
AC service call	$75–$200

Ranges are typical US prices compiled by FixHomeCost. Prices vary by region, home and contractor, so compare 2–3 local quotes.

Common questions

Can I run my AC if the outside fan is not spinning?

No. Without the fan the compressor overheats and can fail, which is far more expensive. Turn the system off.

How do I know if my AC capacitor is bad?

A humming unit with a still fan, a bulging or leaking capacitor top, or a fan that starts after a push are common signs.

Why does my AC fan start after I push it?

The motor is not getting enough starting help, usually from a weak capacitor.

How much does an AC fan motor cost?

A condenser fan motor replacement usually costs about $300 to $700 installed.

This is general information, not a professional inspection. See how we research costs.