I know this is annoying ...
... but AA is not very nice at all to their partner Swiss, at least for the time being. You will not get into the AC with a LX C or F ticket, even though you're flight to ORD is on AA. As the prior poster pointed out, only if you have an AA flight number they will let you use the AC. However, Swiss has a nice lounge with unlimited free drinks in the Terminal you fly out of.