What would cause a fuse to blow?

[6.0DSLPWR]

I have a VIAIR 380C compressor on my truck. I installed the compressor about a year ago. For 10 months I had no problems at all. Then 2 months ago the 30 amp fuse for the compressor blew so I installed a new fuse and used the comprssor for another 2 months with no problem. Until today when the fuse blew again. So I installed a new fuse and climbed under the truck and checked to make sure my connections were tight. I couldnt see any problems with my connections and the compressor ran until the pressure switch cut out. This was in the morning then my truck sat all day and the pressure in the tank dropped(I have a couple POS push to connect fittings that are leaking and I havnt changed them out for compression fittings yet). So I climbed into the truck this evening and the compressor fired up ran for a few minutes then blew the fuse again.

I know a bit about automotive wiring but am not sure where to start looking for problems. The only thing I noticed while under the truck today is that my wiring connections are getting wet under the truck and I have the relay out in the weather(which I know probably isnt the best thing for it, I am thinking about changing the relay for a waterproof one). Would water getting into a connection cause a fuse to blow?

[baddkarmaracing]

Originally Posted by 6.0DSLPWR

I know a bit about automotive wiring but am not sure where to start looking for problems. The only thing I noticed while under the truck today is that my wiring connections are getting wet under the truck and I have the relay out in the weather(which I know probably isnt the best thing for it, I am thinking about changing the relay for a waterproof one). Would water getting into a connection cause a fuse to blow?

your connections are probably getting wet like you said and shorting out i have had that problem before