The temperature of the water changes drastically while showering. Moving the handle to a different position does not keep the water at a constant temperature. Does this mean the mixing valve is shot and does moen warrant this part?

Hi Lionelben:

What kind of water heating device do you have? Do you have an electric or a gas water heater or another appliance like a tankless coil, etc.?

I would eliminate the heating device as the issue by running hot water at the other fixtures in the home for 10 minutes or so and see what happens to the water temps. If you have major fluctuations similar to in the shower then the heating device is defective.

Otherwsie, it certainly could be that the balancing spool at the shower is shot. Moen will replace it at no cost to you by calling 1800BUYMOEN. You will need the model number of the shower valve.

MARK