want to re gas my air con on 2001 w210 before i do could anyone tell me where the low pressure fill conector is located

 

Left side of engine compartment by top of inner firewall/bulkhead.

 

along the side top of the engine.alum tube with a small schrade valve with a black cap on it. The fill unit on the can will only fit the low side so you can't make a mistake.
right side looking into the engine.

 

 

thanks guys what would i do without this site the photo was superb

 

What are your A/C symptoms? If your gas is not low you might do more harm than good by adding R134a. I would run the built-in climate control diagnostics and look at the value of #7 aka refrigerant pressure before adding any. Just to be on the safe side because there might be another reason your system is not working properly. Plus if that is low, you probably have a leak somewhere so you should also inject some dye to locate it.