OP can be more informative. Your questions are pretty vague. What side is it on? high or low? what type of bolt is it? hex bolt? when you say on the strut tower wall, what exactly do you mean? on fender side wall? or firewall?
Maybe more pics of different angle? Because if you are talking about loosing psi where you loosened the bolt, then you are talking about a connection, either at condensor, compressor, evaporator, firewall. all the other bolts IIRC are mounting bolts to the chassis. they run through tab like brackets.
GOod luck bro! Ive redone the AC in my car twice. lol. no fun