A faucet that includes a spray hose uses a diverter valve. Combination tubs and showers also use a diverter valve. The valve is used to change the direction of the water; instead of water flowing out of the faucet, the diverter valve lets the water go out the spray hose. Over time, minerals from the water build up on the diverter valve and cause it to clog and not work. A sign that the diverter valve is clogged is that the water no longer fully changes location. The water pressure will drastically decrease when the valve is clogged.
Turn off the water to your faucet. The diverter valve is normally found under the sink. Open up the cold and hot water faucets to drain out any water still in the faucet lines.
Turn the single set screw that is located at the top of the faucet handle. Depending on your faucet, this screw may also be located on the side of the handle. Use a screwdriver and turn the screw in a counterclockwise direction. With the screws off, pull on the handle and remove it from the faucet body.
Remove the faucet caps with adjustable pliers. Grab the cap with the pliers and twist to remove it.
Slide the spout off the faucet body. With the spout removed, you can see the diverter valve.
Pull out the diverter valve with needle-nose pliers. Scrub all around it with a small brush and some vinegar. This removes the mineral buildup that can clog the diverter valve. Clean around where the valve sits in the faucet as well to remove all of the mineral deposits. If you find another type of clog due to debris, use the pliers and pull out any debris in the diverter or the water hose that connects to the diverter.
Replace the valve and put the faucet back together.