High Pitched Whine

[Seadweller]

I'm in the Tampa Bay area of Florida, so bear that in mind when it comes to temperatures. My wife had the Boxster out, and when she arrived home, as she was pulling into the garage, I heard a fairly loud, high pitched whine. It sounded similar to a dentist drill. It's the first time I've heard it.

I immediately ruled out the SAI, as I can't imagine that would be running with the car at full operating temperature. Turned the car off, the whine immediately stopped. I didn't have a chance to revisit the issue until this morning. I started the car, and the whine was gone. Turned on the A/C, and confirmed both front fans are operating as normal.

It's really hard to tell where noises come from at times, but it seemed to be in the front half of the car, so an engine related cause is not on the suspect list at this time.

Should my next step be to check the high-speed fan operation? I can do that with a jumper wire at the relay, correct? Can that be done with the ignition off? Which relays specifically control the high-speed fan setting?

If I'm off track, suggestions would be most appreciated!

Thanks!