How To Fix Moen Faucet Leaks
By Fixing a Moen faucet leak is easy when you know how. If you don’t know how fixing a Moen single handle faucet can be your worst nightmare and even result in severe damage to the faucet by using improper cartridge removal techniques. There are three different single handle cartridges used in Moen faucets, the #1200 brass cartridge, and the #1225 plastic cartridge, which are interchangeable and pull out to turn on with rotation right and left controlling the temperature, there is also the Moen #1222 Posi-Temp Cartridge, which is only used on tub and shower valves and rotates to turn on and adjust temperature. 
The Posi-Temp provides Anti-Scald protection by balancing the pressure differences that occur between hot and cold water when other fixtures in the home are used while someone is in the shower. Pressure balanced faucets typically maintain a set temperature within +- 3-degrees F.The Posi-Temp Cartridge is easily recognized by its having 2 tabs that extend to the outside diameter of the bore where the cartridge is inserted into the valve body. Despite the differences in the three cartridges once the handle and some of the trim parts are removed the cartridge removal technique is very similar. For the purposes of this article we are not going to discuss removal if the handles and trim the best resource to see how the handles and trim is removed is the parts diagram in the original instruction manual or, finding the parts diagram at Moen’s website.
The first thing you need to do is shut off the hot and cold water supplies to the faucet you are repairing then check to verify that the water is off. The stop valves on sinks should be under the sink. On many tub/shower valves you will need to shut off the whole house. The next step is to lay a rag over the drain so that none of the parts can fall into the drain. After looking at the parts diagram for your faucet remove the handle then stop tube or, retaining nut, and perhaps some other parts as well depending on which of the many models you have to expose the retaining clip.
Use a pick to pull out the retaining clip. The next step is to use a Moen Cartridge Removal Tool to turn the cartridge, turning the cartridge breaks the cartridge free from any bonding of the rubber to the brass bore or, any hard water deposits that hold the cartridge in place. There is a plastic turning tool that is supplied with Moen cartridges but with the #1200 and #1225 is seldom successful. You will probably need to purchase a Moen Cartridge Puller such as the Pasco #7040 to successfully remove the #1200 and #1225 cartridges. Do not use other tools such as pliers, screwdrivers, and chisels you will probably end up destroying the valve body or, at best ruining the ears on the cartridge making removal difficult and expensive for the plumber you will end up calling. The Posi-Temp Tool supplied by Moen with the new cartridge actually works quite well with the cartridge ears riding up the ramp built into the valve body. Once the cartridge has rotated the cartridge is ready to be pulled.
If you have the Pasco tool there is a thumbscrew that screws into the center of the stem or you may simply grasp the stem with pliers and pull the cartridge out. In most cases as long as the cartridge was turning freely the cartridge will pull out. Once the cartridge has been removed inspect the bore where the cartridge was for any bits of rubber from the o-rings and seals removing them if present.
To install the new cartridge you first need to coat the rubber seals with non-petroleum based plumber’s grease, silicone based grease is an excellent choice. In the case of the Moen Posi-Temp Cartridge #1222 you will note on the one of the tabs there is a “HC” marking which must be pointed appropriately towards the hot and cold supplies. In most cases this marking will be up however, in back to back installations it may be reversed. The orientation of the Moen #1200 and Moen #1225 does not matter all you have to do is turn the cartridge to where the retaining clip can be inserted.
Insert the cartridge into the bore and install the retaining clip. Replace all the trim parts and the handle then turn the water back on and check the valve for proper operation. In the case of the Moen #1200 and #1225 check for proper turning of the handle for temperature adjustment with counterclockwise for hot and clockwise for cold. With the Moen Posi-Temp #1222 make sure the cold water turns on slowly at first then as you continue to turn the handle counterclockwise it gradually transitions hotter and hotter. If the temperature selection is reversed with the Moen #1200 and #1225 or in the case of the #1222 the hot comes on first then as you turn it further the cold comes on with some other weird symptoms you will need to remove the handle again then turn the center stem 180-degrees and reinstall the handle. The operation should then be normal.
