I just bought a 1983 240d from a 91 year old lady with all records and the a/c didn't work so I reviewed the records and they spent over two grand on a a/c system. They did a recharge ever year after that too well not me I took the caps off the ports and got lucky I saw a little leak from the value core and replaced it. I then went to harbor freight and bought a a/c vac and gauges. I put a vac at 29 mlb on it and it held. I then put 2oz of meneral oil with die and 2 two cans of frez 12 in it. How cold it is. If all else fails put the die in it and find out where it is leaking and replace o-ring.