AC Evaporator Core Cover Help

[adamsanders]

I took my evaporator core out of the truck several weeks ago to clean and flush for an AC rebuild. I went to put it back in yesterday and could not get the cover to go on. The 11mm stud on the firewall is preventing me from sliding the box on. I have tried every angle I can think of. Do you just have to manhandle into place? I’m trying to not collapse the fins on the core itself. When I took it out a few weeks ago it seems it just popped right out. I’ve read online that the whole HVAC unit needs to come out to reassemble that cover and then put the whole thing back as a single unit. Is that true? Thanks

edit: 91 F250 w/ factory AC

 

[Garbage_Mechan]

Definitely don’t need to remove anything more. I’ve done this before and don’t recall anything special so likely you just need to relax and take a new look at things.