Symptoms
- Compressor runs (you hear a hum or vibration) but the fan blade isn't turning
- Unit may overheat and shut off after running this way for a while
- No cooling or reduced cooling as a result
Likely causes
- CommonFailed dual-run capacitorThis component gives the fan motor the initial push to start spinning; when it fails, the motor just hums.
- CommonSeized fan motor bearingsYears of outdoor exposure can wear out motor bearings until the fan can no longer turn freely.
- PossibleDebris jamming the fan bladeSticks, leaves, or other debris can physically block the blade from spinning.
- PossibleFailed fan motor windingsComplete electrical failure inside the motor prevents it from running at all.
What to do
- Turn off power to the outdoor unit at the disconnect box or breaker before touching anything.
- Visually check for any debris caught in the fan blade or housing and remove it if it's safe to reach.
- With power off, try gently spinning the fan blade by hand; it should turn smoothly with a little resistance.
- If the blade is stiff, gritty, or won't turn, the motor bearings have likely failed.
- Don't run the compressor for more than a few minutes without the fan working, since this can cause the unit to overheat and trip a safety switch.
- Call an HVAC technician to test the capacitor and, if needed, replace the fan motor.
Tools and parts
- Flashlight
AC condenser fan motorSearch: “air conditioner condenser fan motor replacement”
AC dual run capacitorSearch: “air conditioner dual run capacitor replacement”
When to call a pro
Call an HVAC technician to test the capacitor and fan motor; running the compressor without a working fan can cause further damage.
Safety
Use caution
Always cut power at the disconnect before touching the fan or opening the unit; capacitors can hold a charge even with power off.