Heater not working, Exploding fuses
 

Hey guys, I'm new here, my first post and hoping this is in the right spot and I get some good answers.
I have a 2001 tahoe LS , only modification is a flowmaster muffler, other then that its stock.

I went out to the truck this evening , started up and let it warm up, turned the fan speed up and nothing happened, this has never happened, so I tried to change the air location, temp contol and fan speed again, nothing.
So I checked the fuses related to the hvac on the side of the dash, all were fine and looked perfect.
I then checked under the hood, there I found a blown fuse. It was the mini 30 fuse and it was black, so I replaced it with a spare, turned heater on and the new fuse exploded within a second, its not just a blown fuse, its charred black and seemed to have blown very hard.
After that I did not attempt anything else, but for 2 30 amp fuses to blow is such a way, something is clearly wrong.
Any ideas on what I could check or look for ? Everything else on the truck is working fine and as it should, no problems at all, but why this heater/fuse thing came up out of no where I don't know.
Any help would be great, all I've done so far is checked other fuses and all were fine.
I am mechanically inclined, but when it comes to electrical its all greek to me.

What should I do or check ?
Its cold up here in canada, I need my heater back. Lol

Thanks guys

Welcome to the forum... I would try disconnecting the blower motor and then replace the fuse, if it does not blow then the wiring is probably good the blower motor is bad...