I moved into my house 12 years ago and the basement bath was partially finished. I just finished the bathroom, the shower was installed but I ran new line to the mixing valve. I never tried the mixing valve before I finished and now that I am done with the bathroom nothing comes out of the shower. Is it possible for a mixing valve to go bad after sitting unused for 12+ years.
Possibly. Remove the cartridge then turn on each shutoff one at a time. Does both hot and cold work?? If yes, about equal force?? If yes, replace the cartridge. The cartrideg is designed to slow flow on the opposite side, if the pressure on one side drops, as in flushing a toilet. If the pressure on one side is very low, you will get no or little flow.
I don't know anything about mixing valves. It is a single knob that comes out of the shower, where would I find the cartridge and does the water to the house need to be off when replacing the cartridge? I thank you for any help you can give me. If you don't mind, walk me through step by step.