Hi Steph,
Remove the wire from the J8 terminal and check for 120 VAC between this terminal and the J7-9 wire while the control calls for cooling.
If the reading is incorrect, replace the main control board.
- The main control board
Part number: WR55X10942 
Here are the breakdown diagrams and
Parts for GE PSS25SGNABS Refrigerator - AppliancePartsPros.com
Gene.