2010 Chevy Cobalt AC empties when it’s cold outside

[rmay635703]

So basically HVSC Tecs can’t find the leak, I asked for them to preemptively change the little fill valves and they wouldn’t.

Pretty much system stays filled all summer.

Wisconsin 1 day is hot, next cold, next hot again in the fall.

Last 3 years when that happens I find the ac system is empty and won’t engage.

Any ideas what this could be?
Only common failure on this car is bad o-rings.

[nemo]

Had a Ford company vehicle that would do similar. Stop using the AC the system would discharge. The system used some strange spring system to retain the connections. Seem to remember them saying something about bad O-rings. Happened about 3 time, they may have ended up replacing the lines.