There are multiple fans in all projectors. Some have only 2, some have more. My parts supplier lists 4 for that model, with the cost ranging from $50 to $70, depending on which one.
While it could be a fan, I've never had to replace one for any reason. Whine is usually attributed to the color wheel (in DLPs). It is described by some as a "buzzsaw" noise.
Now, if it IS the color wheel, sit down. My supplier shows the color wheel for the HC1500 as costing about $385!! Definitely one of the most expensive I've run across.