2002 Solara - Passenger door speaker problem

The woofer speaker in the passenger door cuts out in cold temperatures ( colder than -5 celsius). The speaker works fine in warm weather, or once the car heater had warmed the interior on a cold day.

Does this sounds like a wiring problem, or a speaker fault etc ?

Is there an easy way to remove the grill in front of that speaker to get a closer look ?

Thanks.