Hi,
I have dual shower heads but one only has cold water. It is a handle, lever type and when I turn it to the left for hot water it doesn't get hot and if I turn it all the way the pressure stops and no water at all. Any thoughts?
Thanks,
Eagle Feather (Tyler)

It is most likely caused by debris lodged in cold water side inlet/outlet in the cartridge. You will have to close water, remove trim, remove cartridge, flush it / clean it - and reinstall. It should work now... Back to you...

Milo got you started in the right direction. However, since you never get hot check both inlets, hot and cold. With the cartridge removed cover the opening with a towel and have someone turn on the main for a moment to blow out the lines