For about a month now, my whirlpool refrigerator/freezer has worked on and off, but it won't maintain the proper temperature. The coils are not frozen over. Using the refrigerator temperature dial, I can force the compressor to come on. By doing that, temperature on both sides (side by side) will go down. However, the temperature does not hold on either side.

How can I troubleshoot this? Could it be the defrost thermostat? How can it test it while in place?

Thank you!