Hi, I just picked up a 1991 560 SEC. When the AC is on, at low speed it cools while driving. When stopped for more than a minute or so, it seems to stop cooling. When using the AUTO button it blows a lot of air, but not cold air. Same when using AUTO and setting the temp dial to the lowest setting. Any help would be appreciated.

The AC system was last recharged in mid 2019.

Thanks for your help