I can not say for sure, I bought the car in Dec of last year. I filled the system with about 2.1 lbs. two months ago and it progressively lost it’s ability to get real cold. The other big problem was air barely blew out the center vent, it blew thru defrost vent, that meant the vacuum element was leaking. There are 6 vacuum elements that control air distribution, they don’t last forever.

Look at the lower right side of the photos I posted in the thread in the link I referred you to, post #1. You can see a little greenish oily tint on the bottom of the evaporator and in the case. It never leaked enough for any oil or dye to come out the bottom of the evaporator core. Also you can smell the oil on the evaporator, it’s quite nasty smelling. Sometimes people with bad evap leaks will complain of the interior of car smelling from ventilation system.

To make the A/C function like it did when car was new I replaced stuff I mentioned in the thread I linked to.

Four of the cars I work on are 124's and all of them have new evaporators. Actually, one of them, a 1992 had a new evaporator 8 years ago, it was done by an independent for prior owner right before I bought the car. My expectation is sooner or later a 124 is going to need either a vacuum element replaced or the evaporator.

If you have to take it apart for an element you might as well do the evap too. That’s what happened on the one in the photos. It turned out the evaporator was leaking, which is what I suspected, and I had 3 vacuum element that also leaked.