I have a twist shower control that controls the water anfd temp that fills the tub and then you pull on the lever on the tup faucet and it turns on the shower. My problem is that when I turn it on cold flows great then I turn it to hot and it slows to a trickle of just cold water. It only happens in 1 of the 2 showers and all of the sinks are great any advice would be great thanks Eric

That one shower mixer is partially clogged on the hot inlet. If you can post a picture or give us the brand/model we can give specific instructions on how to clean the valve, its likely a cartridge or ball

Please tell us the brand and the model number of your faucet, Thanks.

John