The fan will turn on but the blades won't spin.

if fan require an effort to turn it is bad should spin freely

Might have broken the flywheel if this fan has one. The flywheel is the is the round rubber wheel that the blades attach to. If I knew the model of the fan I would know if it has a flywheel.

Check to make sure your blades screws are tight. They could be rubbing against the glass.

A the fan motor is bad. Or b the capacitor is bad. Try spinning the fan motor with a stick or screwdriver.if it spins freely then it might be the capacitor. Take the side cover off and look for a silver round thing if the top is bubbled up or it has oil on it it's bad.But it's got to be one of those.

start capacitor on the cond fan motor

Hi,
If it spins freely when it is not powered then the start capacitor has gone bad and replacing that will fix the problem...
If it does not spin freely and the bearings need oil then check out this tip on how to oil the bearings in the motor...

How to Oil Condenser Fan Motor with pictures
heatman101

With the fan UNPLUGGED, try to spin the fan blade with a pencil or something that will fit through the blade cage.

If the blade spins easily, there is an electronic problem (control or motor) that must be serviced.

If the fan blade is stuck or very hard to move, the shaft and bearing are probably dirty and need to be cleaned. You can temporarily fix this with a tiny amount (a drop) of WD-40 applied to the shaft where it enters the motor. Spin the blade manually to work the oil into the bearing. If the motor spins freely, the dirty bearing condition is verified. To properly clean the shaft and bearings, the motor must be disassembled.

Does the motor spin, but the blade is not turning?
The motor has a D shaped shaft. If the hole in the blade that the shaft goes in is rounded, then the blade will spin. In that case you need a new blade. Vornado can supply that.

Hi,
If the compressor...the black can in the back...is running then the fan should be running...
if it is not running when it should be, check the fan baldes, you may have bent one or more of the blades and now the fan is stuck because it cannot turn...
If so, just bend the fan blades back stright so they do not hit anything...

heatman101

The motor bearings need machine (like sewing machine oil).
Try a quick spray of WD40 or Liquid Wrench, but use machine oil, soon.
Look for an "oil hole" on top of the motor; there may be two of them.