Blower fan fuse pops when I turn on front defroster - Help!

I don't know how in the heck this could happen, but every time I turn on the front defroster, the fuse for the blower fan pops. It's fine on heat/vent/etc, and I have all fan speeds, so the resistor seems to be fine. Anyone ever run into this problem? It's dangerous to not have the defroster working at this time of year!

Hm that doesn't make any sense.

All flipping the selector to "defrost" does is aim the vent doors towards the windshield and activate the a/c.

Strange.

short inside the hvac panel??? that would be my guess. maybe the cable for the vent doors is shorting out the blower wire???

Took some time today and messed around with it a bit. Turns out that the replacement relay I used(I replaced all 4 under-hood relays tracking down a high-idle issue) had different internal circuitry than the original, causing incorrect current flow, and blowing the fuse. :roll: