Adjusting temperature of Pfister, IYLA shower handle (no set screw), Oct 2021

The shower was renovated a month earlier, with this new shower valve installed by the renovator. After use for a while, my wife complained that the hottest temperature from the shower was not hot enough. She asked me to find a way to adjust the shower to make it hotter.

When I looked at the shower valve, I was stumped — because there were no set screws visible.
I found a matching style of the shower valve on the Pfister website, a model named IYLA. I downloaded the various specifications, but not find clear directions how to take the handle apart. Directions in those PDF documents from Pfister stated that no tools were needed for the final installation of the shower handle. The diagram indicated that rotating clockwise would tighten the handle. That seemed strange, because rotating counterclockwise would turn on the water.
I searched various YouTube videos, and found a video of a different Pfister model that showed a part adjacent to the handle should be rotated to remove the handle assembly.

   • Price Pfister NO SET SCREW Shower Han...  
Price Pfister NO SET SCREW Shower Handle Removal
29,509 views Dec 25, 2018

Taking that suggestion, I went back to the shower handle assembly, and found I could unscrew the body of the assembly without moving the handle, and without accidentally turning on the water.
Next I went to a Pfister video which described how to adjust the temperature.

   • Maintenance: How to Adjust Temperature  
Maintenance: How to Adjust Temperature
122,855 views Jan 12, 2011

This video described a different, older model of Pfister, yet it had a similar internal (plastic) washer setup.
It described the “A” and the ”B” and the “C” settings of the washer, ranging from hottest -- to less hot -- to warm temperature settings.
In my dismantled shower mechanism, I found a similar washer. It was set to the “B” setting, which was not the hottest setting. I was able to remove the washer, and rotate it to the hottest setting.
I then reassembled the handle mechanism. I tested the water temperature, and now it seemed suitably hot.
I did NOT shut off the house water for this adjustment, and disassembly and reassembly worked