Moen Posi Temp Question

I Just Replaced The Cartridge In Our Other Bathroom Which Is A Moen Posi Temp, But It Lost Some Water Pressure, Any Reason Why? Or How To Fix It

Sometmes debris is introduced into the pipins system by the valve used to shut off the water. First, remove the shower head and see if the pressure is good with the head removed. If so, clean out the head.

If necessary, then remove the cartridge again and look for debris.