WHich connection is LOW pressure side of A/C on 88 300SE
 

I need to add some 134 with red dye to assist in locating a leak. Can someone tell me which connection on my 88 300SE is the low pressure side? I want to avoid exposions in my garage (and face)! My car was converted to 134 by prior owner. I see one connection on the driver's side on top of an easily accessed hose, so I asusme this could not possible be it. There is another connection that would be a bear to reach right down by the compressor so my guess it that's the one. I just don't want to guess.

it's the connection on the hose going to the firewall on the drivers side.

GET OUT !!! Mercedes actually made the access to the low side THAT easy?! Now I am convinced of the thoughtout quality of Mercedes engineering. I recall adding freon to my 944. Porsche placed the low side input right next to the compressor so you had to get under the car and the best part was that one of the accessory belts ran right over the fitting so you needed an angled line to feed the freon into the system.

I hope you don't take this the wrong way, but if you must ask this question you really should not be messing with it. If you understand refrigeration fundamentals, you can always determine which is high and which is low by tracing the component layout on even a "new to you" system.

To do it properly you should connect a manifold guage set. The set cannot be connected wrong. On the 134 system the high and low side are different, non-interconnectable fittings. At that point you must know which knob to turn to see that you are charging via the low side.

Please be careful, or better yet get someone with a manifold gauge set and proper knowledge to charge it for you. I don't want to see any of our mshop siblings at risk.

We used to have a frequent poster that went by: "Deezel" He was the self appointed "Safety Officer." I expect that he had seen some bad accidents in the past. He was constantly chiming in on threads with safety information of all types. He is missed.

I'm not near as dilligent as he was, but when I see red flags I chime in with safety warnings. I will take the chance of hurting someones feelings or being seen as rude, and in return hope that I can prevent someone from getting hurt.

Be careful,

Your not offending me at all. Safety is important. My mechanic is having his system serviced and since there's not a great need for a/c right now, he said it could be several weeks before he could charge it add some dye and see where I may have a leak. He suggested putting in one can with dye myself since the system was low enough to accept it. Of course I realized this am that I didn't know which was the low side. rather than call him at work, I figured I'd post here.