Replace a Condenser Fan Blade

Replace just the condenser fan blade (motor stays): match diameter, pitch, blade count, rotation, and bore; set the blade depth in the orifice/shroud (typically about 1/2 to 2/3 of the blade inside the shroud); tighten the set screw on the shaft flat; then confirm it runs balanced and pulls the right amps.

Approx. 45 min

Before you start

•Confirmed the blade is the fault — a cracked/bent/eroded blade, lost balance (vibration), or one thrown by a seized motor (if the motor seized, replace it too). The motor itself must be good for a blade-only swap.
•Replacement blade matched on ALL of: diameter, pitch (degrees), number of blades, ROTATION (CW vs CCW viewed from a stated end), and bore (shaft) diameter. A mismatch changes airflow and head pressure or won't pull air at all.
•Power off and the unit safe to open at the top/fan deck.

Tools & materials

Allen/hex keys + nut drivers (set screw), screwdrivers · Clamp ammeter, anti-seize on the shaft (light) · Straightedge/ruler for blade depth in the shroud · Replacement fan blade (matched dia/pitch/count/rotation/bore)

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Isolate & remove

Kill power and remove the fan deck
Disconnect and verify power, then lift the fan deck/motor assembly out of the top. Note the blade's depth in the orifice and which way it faces before removing.
⚠ Lockout/tagout and verify 0 V before reaching into the fan.
Loosen the set screw and pull the old blade
Back off the set screw(s) (they seat on the shaft FLAT) and slide the blade off the motor shaft. Note the depth/orientation. Clean any rust/burrs off the shaft.
Tools: Allen/hex keys + nut drivers

Set the new blade

Confirm the match and rotation before fitting
Verify the new blade's diameter, pitch, blade count, rotation, and bore against the old one. Rotation is the silent killer — a CW blade on a CCW motor moves almost no air and overheats the motor. The blade scoops air in the motor's direction of rotation.
Target: Diameter, pitch, blade count, ROTATION, and bore all match the original
Set the blade depth in the orifice/shroud
Slide the blade onto the shaft and set its depth so roughly half to two-thirds of the blade sits inside the fan shroud/orifice (match the original depth). Too high and it spills air over the shroud; too low and it recirculates hot air.
Tools: Straightedge/ruler
Target: About 1/2 to 2/3 of the blade inside the shroud/orifice (match original)
Tighten the set screw on the shaft flat
Rotate the blade so the set screw lands on the machined FLAT of the motor shaft, then tighten it (and any second screw) firmly. A set screw on the round of the shaft works loose and the blade walks off at speed.
Tools: Allen/hex keys
Target: Set screw seated on the shaft flat and tightened firmly

Balance & verify

Reinstall, confirm balance and amp draw
Hand-spin to confirm the blade clears the shroud all the way around, reinstall the fan deck, then run the unit. Confirm it runs smooth (no vibration/wobble = balanced) and the motor pulls within its rated FLA. Excess amps or vibration means a wrong blade or a bent shaft.
Tools: Clamp ammeter
Target: Smooth/balanced run; motor amps within rated FLA; blade clears the shroud