I am trying to locate the low and high side A/C ports on my original 1989 300E AC system. It is the original R-22, not R-134. I have a recharge hose and a can of R-22 with a leak detector but I cannot tell which is the correct port. There is a port on the top of the car near the driver side fender in a bigger pipe (green arrow) and there is a port which is located near the condensor/ compressor/headlights closer to the front of the car and quite low (yellow arrow). I have attached pictures of both ports. I'd really appreciate it if somebody can tell me which one is which. I have the original MB shop manuals for my W124 but they do not specify the port location.
