Jargon: ADC = Adaptive Defrost Control. If you don’t know what that means, this post will give you a quick background on it==> http://fixitnow.com/wp/2010/06/27/adapting-to-adaptive-defrost/
This procedure applies to the newer model Frigidaire/Electrolux refrigerators with ADC. Example model number: PHSC39EESS
To activate manual defrost, press and hold the Freezer temperature UP (WARMER) key
while pressing the Fresh Food temperature DOWN (COLDER) key 5 times within 6 seconds.A “d” in the freezer temperature window and “F” in the refrigerator temperature window
will display when the heater is activated.“d” and “F” will be displayed until the defrost cycle is complete. (approx. 8 minutes)
To deactivate manual defrost, press and hold Freezer temperature UP (WARMER) key
while pressing the Fresh Food temperature DOWN (COLDER) key 5 times within 6 seconds.