Compressor is more than likely locked up or you have a short in the wiring.
Try unplugging your AC compressor and see if it still blows the fuse. When you turn on your defrosters you also turn on your AC.
this is because you have a short in either the the ac circuit or the fan/blower circuit. You'll know know which one by turning the fan on without the ac, and if it doesn't blow the fuse then you know it's the ac circuit.
a fuse could be blowed or your ac needs to be charged.(or both)
check the fuse
No, it is not a blown fuse. Once the fuse blows it will never work until you replace the fuse. Sounds like a loose connection in the wiring or a loose fuse.
Bad clutch on compressor, unplug the wires from the AC compressor, replace fuse if doesnt blow fuse its in compressor, if blows then gounded wire
Check to see what stops working when the fuse blows. If it is the compressor itself, then either the ac clutch or the ac relay has probably gone bad.
Put a new fuse in. Turn on the ac, make sure you have enough freon to allow the PCM to engage the compressor. If it pops when the ac is turned on then the compressor clutch coil is most likely burnt. The fuse blows to keep the rest of the system from frying. I recommend replacing the the whole compressor. Good Luck.
could be a shorted fan,try unplugging the fan and turn on the ac and see if it still blows,dont run it too long with the fan disconnected because the ac pressure increases because the freon is not being cooled.
Probably needs freon.
I had the same problem it was a shorted wire under the driverside causing the fuse to blow when you turn the ignition my downstream oxygen sensor wires shorted out (melted and fused together). check for anything shorted out connecting that fuse.
Try using a higher size fuse you have a short in the wireing