Stand-up heating no longer works

Moin together, have been having problems with the SH with my V70D5 MY2002 for a long time. It just doesn’t work anymore, despite enough diesel in the tank, full of battery and even standing area. At direct start, the display goes short on ON, after approx. 2 sec on off. Ok, at the current temperatures, that’s not so bad, but the winter is again at the door. Has anyone had similar problems? Greeting Tom