I'm in a one story 3 bedroom 2 bath home. My shower in the master bedroom (which is the farthest from the hot water heater in the garage) gets scolding hot. My shower closest to the hot water heater gets luke warm at best no matter how long I run the water for in that bathroom.

I can't figure out why the closer shower won't heat up. The hot water tap to the sink in the closest bathroom will get scolding hot, so I believe getting hot water from the heater isn't an issue. Could this be in an issue with the tap to the shower? It's a single mounted tap that increases from cold to hot as you turn it counter clockwise. Any thoughts on where to start?

Thanks for any advice!

What the above posters say. There is an adjustable stop on the valve that limits how far it your valve will go.

The above!
The limits on the other shower are set lower so kids can't burn themselves.

Thanks everyone! This resolved the problem. I had no idea showers had their own temperature limiters.