After shopping, I was parked in a parking lot and the engine was off. The radio powered itself off to conserve energy and then I heard a loud crack sound from behind the dashboard. There was no smell of any kind - no electrical burning smell. It had the sound that happens when a PCB board is broken. After waiting a few minutes, I started the car and everything seemed to be functioning normally. I haven’t had any problems with the car since then. Can you tell me what caused that loud crack noise?
Unfortunately, pinning down noises can sometimes be tricky - especially if the noise is not easily and consistently reproduced. However, in my years of working on cars, I think I may be able to name a few possibilities based on your description. It may have been a door in the HVAC blower case moving after the car powers down. It could also have been a pop noise from the metal case of the radio contracting as it cools down. Some cars have speakers on the dashboard as well. It's possible the crack could have come from the speaker as the radio was shutting off.
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