Originally Posted by lulu1212
In case I adjust the valve to the full extent and still having just warm water what else can be the problem?
Providing the valve is not defective from the factory, Debris has entered the mixer. This could be grit from emery cloth used to clean copper before sweating joints, tiny pieces of plastic from the connection of plastic pipes, sediment from your water supply, just about any foreign material will interfere with the operation of the brass barrel that needs to slide freely inside its sleeve. If you remove the guts from the valve body and shake it longitudinally you should hear the piece slide back and forth inside. You will not or it will not slide very well. Open it up and clean it out - spotless. Flush out the pipe before reinstalling. I recommend a whole house filter to keep new junk from fouling it up again.