I have a Moen shower facet, one knob (hot and cold mixture). The hot water does not come out. The shower has not been used for 8 months. I turned it on and nothing but cold water. When turning it to the left, (hot) nothing. The only 3 things I can think of is forzen, bad valve, or clogged. I was thinking frozen at first, but all other hot pipes sharing the hot water are fine and it’s in the center of the house. If forzen, it would have to be the pipe going from the sink to the tub, under the tile, between the first and second floor. I heated up the room for days, but still no hot water. Not sure what to do. Please help! Thanks, Tom