My 2003 CVT has started gving me a strange noise. No warning lights or apparent performance issues.

I'd describe the noise as a constant "hum" or "whirring" that comes from the engine compartment only when the car is moving. It seems to change pitch a bit the faster the car is moving and continues the entire ride, whether accellerating, decelerating, or otherwise. It's most noisy and noticebale at about 40 MPH. Faster and it's still there, but wind and road noise start to drown it out. I wish I could describe it better.

It almost sounds as if something is spinning without resistance, like a fan or motor or something. Weird.

I'm at 87,000 miles, with no extended warranty. I'll take it in this week to the dealer, and am curious if anyone has any ideas!

 

Not a likely culprit, but...

Are you sure it's NOT coming from your radio?
If you're not sure, turn the radio completely off. If you have an external amplifier added to the system, it could cause this interference as well.
You would hear these sounds from your speakers.