Here are your parts
Replacement parts for WHIRLPOOL ED5PHAXSB00 Refrigerator | AppliancePartsPros.com

Here is the tech sheet
http://www.servicematters.com/docs/wiring/Wiring%20Sheet%20-%20W10142162.pdf

Could be that the bi-metal (defrost thermostat), Item 6 in Section 9, is not opening so too much heat is being generated during a defrost cycle.
The defrost cycle is usually a fixed amount of time with the adaptive defrost board determining how often the unit goes into a defrost cycle.
Once all the frost/ice has melted off the evaporator coils the defrost thermostat should open killing power to the defrost heater. The defrost cycle will continue for the rest of the defrost toime but the heater will be off.

Remove it from the unit and check it with a meter. It should be closed (0 ohms) when frozen and open (56,000 ohms approx) at room temperature.
Also if it looks bulged out it needs replacing.

May also be that your control thermostat is going intermittent, not closing when it should.
Usually if the unit is off and you just turn the temperature dial and it starts up his is an indication of a thermostat problem.

[COLOR="Blue"]I noticed the drip pan was completely dry. Does this mean the defrost cycle is not working?[/COLOR]
I would doubt this. As a defrost problem will not clear itself so you would have to manually defrost the unit to get the unit to work correctly again.