Working on developing my diy skills and have run into a good one. I was replacing the cartridge out of a moen tub, because the cold water was no longer working. After removing it i decided to test if the lines might have issues. With the valve out and the cold water mains turned on there is no water coming out of the faucet housing. How ever if I turn on the sink, water runs out of the tub faucet housing, slowly but it does run some.
Any ideas on next steps or a direction to go?