Little hot water to bath/shower but pressure is OK
We have an American Standard Hampton single handle bath/shower set that was installed in our remodeled bath about 8 years ago. All of a sudden, there's barely any hot water to the tub or shower, although everywhere else we still have nice, hot water (even in the bathroom sink). So, I've read through here, and done searches, but haven't found anything specific to my faucet type and/or issue.
The water pressure is still good, but it's barely warm. I should say that the AS shower head is not the one we are using, we've got an older Shower Massage shower head on it. The issue just isn't with the shower, but also the tub faucet.
I found the diagram of the unit, but need some detailed instructions on what my husband and I need to do.
Thanks!