I just had this problem a week ago. In my car the problem was as short cuased by a wire harness in the engine compartment which had become detached from a mounting bracket and eventually damaged. Something is shorting out and chances are it might be the same thing. How it became detatched I have yet to discover. All I can say is that you should have your local volvo mechanic check it out before you melt something.
volvoboy of georgia