Senator 24v Locking for interior fans will be HAPPY!!!!

Servus, I’m just about to breathe life into my senator 24v again… so far it’s been a good thing, but now I’m facing a problem which is really not sooo great in winter.. When I turn on the blower it takes about 3- 4 minutes to get a smoke cloud out of the fuse box on the way.. Grud: The 30A fuse for the fan is so hot that the housing of the fuse is smeared!!! No matter if I take 20A or 30A the housing melts… g this problem or can help me?? Because driving without ventilation is hardly possible at this time of year… Greeting KW200