I suppose it's possible for either of those two systems to fail and draw more power than usual, but I'd say it's not very likely.
The way to find out is to measure the current-draw using a meter that measures amps, and pull individual fuses to identify the circuit branch that's responsible. If you don't have a good multi-meter, I'll bet you know someone who does.
See this thread for more information and tips:
Gotta draw...
especially posts 11 and 12.