Jeremy in Humble wants to know, he says, “I have a single handle faucet in my daughter’s bathroom and the hot water isn’t working.” He’s heard you describe these cartridge things, he wants to know, does he need to replace just that, or the faucet, or how does it work and all that.
Usually, if it’s a single handle, there’s a cartridge, or a rebuilding kit depending on the brand. Here’s the difficult part, every brand is different. There’s not just a one-fits-all, so you have to know what it is, and yes, it’s right behind the handle, as you remove the handle. Make sure you turn the water off to the house. You’ll have to pull the parts out. Probably go down to a plumbing store and say, “This is what I got, do you know what it is?”, and see if they can get you one. Hopefully, you can get the replacement kit. They’ll have little o-rings, springs, whether it’s a cartridge or a little ball with holes in it, but they’ll have little parts and pieces, you replace all the insides of.