After much searching and trial and error, I'll have too ask.
How do I convert a .hex file to a .asm file in MPLAB IDE v.6.40.
The hex file is for a PIC18F452. I import the file and can see it in program memory but I cannot do a build.
A hex file is an assembled file, ie it's already compiled. You can't recompile it.
If you want to convert it into a asm file, ie disassemble it, there are disassemblers around that can do it. But the result would be rather unintuitive to a human user as all variable names would be garbled.