So why are you replacing the headlight motors? Are you sure there is something wrong with them. If not working often the problem is the control module.
I've never taken an gen 2 motor apart but believe there are little shock bumpers in the gear mechansim that pretty much just fall apart over time. Rodney Dickman sells replacements.
As for the a/c 'not working'. That usually means there is no refrigerant but that in itself can lead to other problems the worst of which is known as 'black death'. Only way to tell is to remove the orifice tube and look at it. If covered in black gunge then the whole system needs flushing and the compressor, accumulator and condenser need to be replaced, the whole system purged or air and filled with the correct amount of lubricant and refrigerant (R-134).
If it just needs a charge and was never converted then you might get away with refilling it with R12 but be warned that R12 is VERY expensive as it is no longer being made (affects ozone layer and all that).
While a/c systems 'look' simple (it's just a pile of tubes and a pump), they are not. Just getting the system to seal is a job and a half!
If you can find a REALLY GOOD shop to work on it then that might be the better option for the a/c but be warned, most 'regular' shops know how to purge/fill the system but that's about it and with Fieros being 35 ish years old, nobody has the doc or knowledge any more either.
Anyway, all that side, good luck and welcome to the forum, the happiest 'Fiero' place on earth!
[This message has been edited by ltlfrari (edited 07-29-2020).]