So the signals don't go thru the relay but the headlamps do, right? Also I was thinking that the relay coil draws amps too. But as has been said, to all of a sudden start blowing the fuse, it may be a short or some component failing like the relay itself, a bulb or the flasher. Check all wiring involved before upping the fuse. I agree with jorb. The turn signal bulbs are only on for 1 blink at a time, so the draw against the fuse is not constant. Leans towards something else wrong. Put 4 new bulbs and a new flasher unit in with same 6A fuse and see. If no improvement, Draw yourself a schematic of how the headlights, relay, signal bulbs, fuses, headlight switch, stop switch and heater are wired and study it.
