Thought for sure I needed new brake pads. Then I thought this may be a wheel bearing. Then it may be a bigger problem. And THEN- I turned off the heater fan and the problem went away.

Any idea as to what it could be? It only happens when I am rolling to a stop and have the fan turned on. It's a 06 CTT-S.

 

The blower motors are known to crap out. I replaced mine on my '05 but it pretty much made noise any time it was on. Sure you aren't just hearing as the car slows and gets quiet? I know that's how I first heard mine.