On Jun 25, 10:21 pm, wrote:
My shower control is the single-handle type. Turn it a slightly to
get cold water and turn it 180 degrees to get full hot water. I
notice that if I connect the cold water line but do not connect the
hot water line then the valve does not let any cold water go through
regardless of the valve handle angle. Is this valve broken?

It is likely a pressure balanced faucet, which restricts flow when the
pressure drops on either side to prevent scalding. Hook up the other
side and see if you get anything. If it works, it isn't broken.

JK