1989 300E A/C Port Location
 

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. :confused:

First, your car uses R-12 and not R-22. Surely this is what you have on hand and simply typed it wrong. (R-22 is for things like residential HVAC units)

The larger diameter hose is the low side and the small hose is the high side.
The fittings are, as you know, the same.

thank you for your help - i mistyped it - it should be R-12. I just want to confirm - the larger hose is on top (its the green arrow) right?

Yes, the larger hose with the green arrow is the low pressure side connection.