Checking antenna amplifier
WARNING: This page is about a different car, the 2002 Volvo C70, 2001 Volvo C70, 2000 Volvo C70, 1999 Volvo C70, and 1998 Volvo C70. However, it is still accessible from the selected car via links, so may be relevant.
Switch on radio and tune in to a weak station. Turn up the volume and go to the back of the car. Listen to the radio while disconnecting the power supply. The station should sound weaker or there should be more interference.