I have a Simmons Temptrol model C shower(no tub) single handle which stopped giving out any cold water. It will work fine on full hot but just gives a dribble when turned towards cold. I thought at first the head was clogged so I replaced that. Next I tried to clean the cartridge with lime away - no good. I called around to find a new cartridge and had to special order it. Came today but I still get no cold water. There is another shower running on the same hot and cold water lines and it works fine. I can see the entire shower fixture from an access behind the shower but don't see anything else which could stop the cold water from entering the fixture. Help !!!!!!!!!