The other night I started the XF after seeing a movie. While driving through the parking lot, I heard a sound like a clicking relay. Two days later, I hear it again. It sounds like it's coming from behind the glove box. The car runs fine, and everything seems to be working fine. Any ideas what this might be, before I dive in? It's intermittent, so it might be hard to find.

 

Was you fan off? If it happens again turn on your fan and see if it stops. If so check out these posts and you will find the answers.
http://www.crossfireforum.org/forum/...s-stopped.html

 

More likely this is the problem, same symptoms I think.
Clicking noise

 

As stated above check to see if it is when the blower motor is on. If so it might just need to be cleaned out.
If not listen closely to where the sound is coming from and report back.

 

I don't think I had the blower motor on at the time, because the engine was cold. I will try the blower when it does it again, and post what happens.

 

Both of my Roadsters have done this. I never really got to the bottom of it, I find that if I move the driver/passenger "heat wheels" in the HVAC panel, it seems to stop in a few seconds.

But see that other link 100/80 gave you....

 

FWIW, It happened again today. I turned on the fan, just one click, and it went away.

 

Did you ever solve your problem with the rattling noise? I noticed the same on my 2004 coupe. Thanks

 

I didn't fix it yet. It only happened only one other time, and turning on the fan stopped it. I'll check it out in the spring.

 

I occasionally hear a clicking right after start-up and always assumed it was part of the airbag system checking to see if there was a passenger in the seat. I never tried turning on the fan. I think I hear it more in my roadster than in the SRT6.