How to Troubleshoot & Replace Whirlpool AP3177209 / 4176691 Thermostat

Researching your website, the most likely culprit was the thermostat and/or thermal fuse. I decided to replace both, in addition to a new quick-connector purchased at Lowe's. After unplugging the unit, I removed the quick-connector from the tank and used pliers to slide the clear tubing clamp up so as to remove the tube from the top of the tank. As long as one doesn't activate the OFF/ON cap at the spout it isn't necessary to turn off the cold water supply. Once the water lines are disconnected, I removed the unit and inverted it to rid it of trapped water. Two small screws secure the faceplate through which the temperature control extends, and that plate was removed to access the thermostat. I also removed two screws securing the top of the tank, which gives access to the thermal fuse's connection to one lug of the heating element. Utilizing a 5/16" nut driver, the thermostat can be removed and the two wires which attach to it are removed (spade connectors). Connect the appropriate end of the thermal fuse and reconnect the power wire to the new thermostat and reinstall. Reconnect the other end of the thermal fuse to the heating element lug, and the repair is complete. Install the tank top and temperature control panel and connect the two water lines, and you are good to go. 

I installed the two parts...and it works!