My fuse on the engine compartment fuse block for my HVAC blower motor has blown. It has melted so bad that the prongs for the fuse are stuck deep down in the block.

That usually only happens when somebody stuck a fuse in there that was of a higher amperage than is called for, and it didn't blow when it should have. Now as for your question, if the plastic components in the fuse box have melted, unfortunately you are going to have to replace the whole thing, especially if it got so hot to effect adjacent fuses. The wiring to the fuse box may be scorched also, so for safety's sake it needs at least a thorough inspection, OUT of the car, or you risk electrical fire..not good to state the obvious

There are two fuses for the HVAC blower in your Grand Am. The one in the engine fuse block is 20 amp and it supplies full 12 vdc power to the motor when speed #5 is selected. The #1-4 speeds are fused from the passenger side fuse box and power goes through a resister bank to regulate the speeds. --- The fuse melted the holder because you either use #5 all the time and the connection became loose or there is a problem with the blower motor. Head over to GAOwnersClub.com for info on repairing the blower motor and fuse block.