where are the high and low A/C taps on an 88 190E
 

I'm trying to troubleshoot the A/C on my 1988 190E 2.3. The site glass on my drier is empty...so I want to put some refrigerant in to look for a leak. I've never done this before. I found the schraeder valve near the exit of the condensor but I'm not at all clear if this is the high pressure port...and if so where the low pressure port is.

The pictures in my Haynes manual and shop CD are so dark...I can't really tell what's what.

Can anybody paint me a picture of where I should attach the lines form my A/C manifold with gauges?

Thanks

Steve

Low side should be on the suction hose assembly.............

Low side is on top of the driver side fender next to the shock mount. Should have a black cap maybe blue for low.