Hello good people, here I am again asking for help from the Benz lovers.

I have a 1988 300 SE.

Recently I have been having a few issues with it, this is the latest one, my Air conditioner.
When I get in the car, the A/C is cold.
If I travel for about 30 mins, it quit cooling.

I can pull over the side of the road, cut the engine off and restart, the A/C will resume cooling or another 20 to 30 mins, I am lost.

I pulled the relay and opened (Klima) nothing seems to be out of the ordinary.
Sometimes when it rains, the same issue happens.
At first I thought that water was getting under the hood of the car, but non-to that effect.

Can someone help me?