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.

Attached Thumbnails

   

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.

__________________
02 S500
92 500SL
92 400E (Sold)
87 300E (Sold)
83 300D Turbo (Sold)
75 300D (Sold)
74 240D (Sold after 20 years)

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.

__________________

1993 190E 2.3
2001 SLK230
1971 LS5 (454) Corvette Convertible