Quite likely the motor itself.
This car shares a lot with the Corsa of same age. The Corsa, when new, gave a lot of heater motor problems. We had them as BSM school cars and many were replaced under warranty as they seized up. Often putting on full speed would wake them, then a lower speed could be selected, but this carries a risk of overheating wiring if they fail to respond. Not something we cared about at the time, as not our cars, and they'd be replaced (whole car) if we had a small fire inside. We (the instructors) reckoned Vauxhall might pay more attention if one or more had a small fire. Our local Vauxhall dealer was changing them in less than an hour they got so good at them.
