1995 Cavalier air conditioning

The upper line on the accumulator has blown off its connection. What would cause it to come off? I have threaded it back on but as of yet have not had it serviced yet. What can I expect?

2.2 litre engine, 1995 Chev Cavalier

Possibly a clog has caused it to blow off, but not likely. Chances are the fitting vibrated loose over time.:disappoin