The valve is for emissions air injection and won't affect the AC.

You need to look for a white plastic line that runs from the intake manifold , along the engine wiring harness and to the passenger side of the car. The line should end in the under hood computer box on the passenger side.

My 97 C280 with the same engine is set up like this and I think my 97 E320 parts car si the same as they share the same engine series.