Fluxuating water temperature

[rickg]

We had a Moen single handle Posi Temp valve installed in our shower about 4 years ago. Over the last year it seems as though the temperature is fluctuating on the hot water side. Some days the handle has to be all the way in the hot range, other days you can put it barely in the hot range, both getting the same temperature. The water pressure also decreases when it is way over on the hot side. I've removed the cartridge and cleaned it according to Moen's instructions, but the problem continues. We also recently replaced the hot water heater (for other reasons) but it has had no effect on the water temperature fluctuation. Any ideas of why this would start happening all of a sudden and is there anything to do to fix it?

[Peanut9199]

There isn't much to the Posi-Temp valve.
There is three different kinds, does your have stops valves built in on the hot and cold?
If yes you may want to check to see if the stop valve is opened all the way or is not partially blocked.
If not than the only other thing it can be is the cartridge, which you should be able to get a new one under warranty from Moen or the store you bought it. The model number on the cartridge is 1222.

http://www.moen.com/shared/pdf/62370pt.pdf