How do I get to the valve cartridge to replace it?

In the summer time, in the desert of the southwest, this is standard. but if you do not live somewhere that is hotter than hades in the summertime then perhaps the moen diverter cartridge has failed. Unfortunately you will need a special tool to remove moen cartridges for inspection/replacement. Fortunately, you can purchase the tool at most any hardware store including home depot and lowes, if you wish to inspect it yourself. just text me back if you have any more questions:)

You need to purchase a replacement cartridge before trying to remove a defective Moen cartridge. Always buy genuine Moen. If your valve turns on and off with a pull/push action you need part number 1225B, otherwise you need part number 1222. The 1200 cartridge will work in lieu of the 1225B but is more expensive and no longer used in Moen valves. There is a tool that comes with these cartridges which looks a bit like a white plastic cap.with notches on one end and a square head on the other.
Once the clip has been removed the only thing keeping the cartridge in the vslve is old sticky lubricant. Place the tool over the cartridge end and rotate as necessary until the notches are fully engaged and it no longer rotates. Using pliers or a wrench over the squared end, twist the tool back and forth several times. Remove the tool, and using pliers, pull the old cartridge out. Put the tool on the replacement part and insert it back into the valve. Lightly tap on the squared end to make sure the new part is completely seated, then use the squared end again to turn the cartridge as necessary to align for the clip to be reinstalled.

Remove the faucet handle and trim. Close of the check valve stops on each side of the valve body with a flat screwdriver. Remove the balancing spool and Moen cartridge. Look for and mineral buildup in side the faucet and on the spool or cartridge. If there is buildup on the spool and cartridge, place them in a large bowel with a cup of vinegar and a teaspoon of baking soda. The solution will remove the buildup in a few minutes. Replace the Moen faucet parts and test the faucet. If there is buildup inside the faucet body, use a wire copper fitting brush to the remove the minerals from inside the spool and cartridge tubes of the faucet body. Turn the stop valves on just a little to wash out the debris before reinstalling the spool and moen faucet cartridge. If the is is still no pressure on the one side or the other, turn off all the water to the house and remove the check valve stops, clean them as well and the inside of the faucet. If all else fails, replace the stops, spool and cartridge. Beyond that, the water supply lines may need to be flushes with the same solution.

you need to get the moen cartridge removal tool at home depot or lowe's

Call Moen directly. They will ship what you need to your door, for free.

It sounds like the valve is a manufacture defect where the cartridge sits.Hope this helps.

Assuming you have a single handle valve, Moen has 2 types of cartridges. The Posi-Temp (replacement cartridge # 1222) turns on and off simply by turning the handle left to right and right to left. The Moentrol (replacement cartridge #1225B) turns on by pulling on it. Handle style does not aid in identification.

Buy your new cartridge before you start and buy genuine Moen! OEM cartridges can give Moen a bad name.

Once the water to the valve is off, remove the handle.

The procedure is the same for either type of valve so use the link below as a reference.

Firmly grab the temperature limit stop and pull it off the valve body. Using pliers, pull out the brass retainer clip. Place the notched end of the white plastic tool that came with your new cartridge onto the old cartridge and rotate as needed until completely seated on cartridge. Put a wrench onto the squared end of the white tool and turn back and forth several times. Remove the tool, grab the brass center of the cartridge with pliers and pull the cartridge out.

Briefly turn the water on ond off to flush the valve of any possible lingering particulate.

Insert new cartridge and use white tool to assure cartridge is all the way in then use the squared end to rotate the cartridge as necessary into an alignment position to reinstall the retainer clip.

http://www.moen.com/shared/pdf/3170pt.pdf

Your Moen valve is equiped with an anti-scald device (as part of the valve cartridge) which prevents someone from getting scalded by hot water if there's a sudden demand for cold water, i.e. a toilet flush, washing machine filling, etc. Fortunately Moen stands behind their products and will provide a new cartridge.
Contact Moen and describe your problem.

replace the cartridge if defectis not obvious.

there is a little plastic tool that comes with a new cartridge....you use it to turn the cartridge back and forth....breaking the seal that has formed between the rubber on the outside of the cartridge and the inner wall of the valve. After doing that you should be able use a pair of channel locks to pull the cartridge out.