[cordell tech service]

Evaporator Icing Up After Many Manual Defrosts, Compressor Runs Quiet And Appears To Be Neutral On Temperature On High And Low Sides, Unable To Tell Whether The Electronic Control Board Is Turning Defrost Circuit On At Proper Times Or Sending Current To Fire Heater. Need Info On How To Trigger Defrost Circuit At Control Board Or To Test Control Board Assembly. Is There A Schematic And Test Procedure For Control Board Assembly Available?

[PS Volunteer - Appguy]

No easy way to force motherboard into defrost. Go to website www.applianceguru.com/forum1/3075.html You will find all the info you need there.
Rather remarkable piece of work here as GE has not provided service info on most of the GE digital refrigerators.
As noted you can force defrost with a jumper from J11 to J9, then monitor current. Assuming fridge is freezing , this should supply current to defrost coils. If not working, you have a bad heater or defrost thermostat. If this works, you have a bad mother board