My Dodge Ram needs a little R134a since the A|C isn't blowing very cold. The low side port is on a plate under the throttle body. It is a female threaded fitting with a recessed valve stem. Do I need a special fitting to be able to access this port so that I can add a little R134a? When I do a Google search, most of the pages I read tell me to hook up the R134a can hose to the high pressure side, which I know I should not do.