Of course this would only happen to me....

07 S60 2.5T with 197k - driving last week and heard what sounded like I hit something as the sound went front to rear on in the car. Saw nothing in the rearview but started smelling a burning smell from vents. I chalked it up to someone leaving a parking brake on as I cruised down the highway, closed the sunroof and activated recirc on the ECC.

Smell is still present.

Pull over and nothing obvious from engine bay, pop the glove box as my suspicion was maybe the HVAC blower and noticed the smell was strong in the area. Drove home, pulled the cabin filter but was not sold on my theory. Became frustrated and parked the car, went inside and had a beer.

Next day I get into car, figured why not roll the dice and started it up. Idled down, engaged drive and ECC started blowing warmer air as engine warmed up. As I pull away from my house I noticed by stereo sound stage was off and had no rear audio. Turned radio off and on, as sometimes have erroneous experiences since installed the GROM audio with stock Sirius tuner, reset usually resolves it. Still no rear audio so switch to FM, same deal. Adjust fader to rear, no audio and it was at that moment the burning smell returned. Put two and two together and determined shorted item in radio, turn it off and smell goes away.

Replaced the radio with a used unit from ReVolv in Central MA and good to go. To be honest my previous HU650 must've been on the brink of failure for a while, slowly fatiguing after years of service as the "new" HU650 has better clarity and brilliance.....for a stock, non Dynaudio setup.

Reason for sharing - well if you, or someone you come across on the forums has an electronics smoldering smell from their vents you may consider the radio. I pulled the cover off, and an IC chip on the amplifier PCB was shorted and charred.

Happy Fall everyone!

Regards,
Steve