The surface of the heater pad during installation

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.

Fig 1: Identifying Bubbles And Kinks In Pad

Courtesy of VOLVO CARS OF NORTH AMERICA.

CAUTION:

There must not be any bubbles or kinks when the heater pad is bonded to the foam filling.

Bubbles and kinks increase the risk of damage to the pad during use.
NOTE:
This applies to the entire surface, but to the heating wires in particular.