Originally Posted by
emcampbe
The issue is that UA and AC in EWR are not well connected - the pier in Terminal A that AC uses is separate from the pier UA uses in A, and so you have to clear security in the UA pier to use their Club. Because the UA shuttle from C-A only stops at the UA pier, same issue with needing to use the one in C - though you could use the lounge in C, then clear security in the AC pier.
AC flights depart in the same pier as UA flights in Terminal A now. AC flights typically use gates A22-25, and UA uses the other A20-28 gates. OP can use the United Club in Terminal A, which is similar to the previous AC EWR MLL.