Recently after not using the tub in my 2nd bathroom I found that when I turn the knob to the hot side the water flow nearly shuts off. This is the only faucet that is experiencing this problem in my home. What do I need to do to fix this?

Help us out a bit... single handle... two... three.. Also, name on valve if possible? How old is bathroom... even a guess will help.

Ok my home is only 4 years old. The only name I see on any part of the plumbins is WATCO on the clean out cover. The faucet is a single handle that just turns one way and the further you turn it the hotter the water gets. Is this enough info?

Yup... enough info. I would sugest that you shut water off to the shower ( may need to shut main water shut off to home for this to happen... bleed pressure off from other faucets before beginning job)... remove handle and then remove the cartridge assembly of the tub valve. Then you want to observe the cartridge and the internal body of the valve.. anything loose.. or say... missing or disintegrated..

If nothing obvious... with a friends help (stands to side of valve with a large cloth)... go to water main and pulse the shutoff on and off... idea is to free the valve of any foreign matter.

Then re-install the cartridge. Turn water on... install handle and check the hot water. Did this do it.. If it did.. GREAT! If it did not then you may have a defective cartridge. You would need to remove the carttridge and take it to a plumbing supply house in your area... they should be able to get a replacement.

IF my answer helped please rate my answer below... thank you.