H'mm. I totally agree with Dave's comments. There is no extra shut off valve per say in the hot water line.
Question, does the cold water in the shower work, just not the hot?
You can take the hot water knob off the faucet and unscrew the valve assembly out of the faucet. Something might be clogged in the piping behind the faucet. That faucet is an O ring seal type. When the knob is rotated enough the O ring seals the water from coming out or by how much.
There is one semi far out stretch on what "might" be happening and it is unique the the T264SR due to its floor plan. See this pic below out of a write up I did for a friend who has a 2005 T264SR. It shows the low point drain valves under the bathroom sink.
The hot water low point drain is a 2 way valve. When it is open, the water in the hot water lines drains out on the ground. By odd chance do you have that low point drain valve partly open? If so, you could be losing your water to the ground inplace of going to the shower.
2005 T264SR low point drains
Hope this helps
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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