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Parts for Whirlpool GX5SHDXVQ02 Refrigerator - AppliancePartsPros.com

See the attachment for the tech sheet.

It could be a defrost problem based on "ice crystals in the back "
I am assuming that the compressor is on all the time except when the unit goes through a defrost cycle.

I would try to force a defrost cycle, see the tech sheet.

If the ice disappears and the unit starts working OK then it is a defrost problem. In this case it is probably a bad control board.
Note if it does not defrost then you will have to do more trouble shooting.
Remove the rear cover in the freezer so you can check the evaporator coils better. If they re clogged solid with frost/ice then it is a defrost problem so you will have to check the defrost thermostat and the defrost heater with a meter. If both are OK then replace the control board.

Check that the compressor is on. You can usually hear it but also should be able to feel it vibrating.

Also check that the evaporator fan is on when ever the compressor is on.

May also be a problem with the damper. It regulates the amount of cold air from the freezer that is blown up into the fresh food section.

Below is a good link with lots of info on refrigerator troubleshooting especially in section 1.
http://www.applianceaid.com/refrigerator-help-section.php