I couldn't find the service manual, but have seen quite a few of these fridges. it has a fan in the freezer that blows air into the fridge. The fridge temp is controlled by the damper at the top of fridge. It should be open if its not cold enough in fridge. If its open and not cold, either the freezer fan is bad or its frosted up (most likely)
It has the Jazz board that goes bad frequently. If it is frosted up, I usually force it into defrost, if it goes into defrost then I know the heater and bimetal are good and I replace the jazz board. If it doesnt go into defrost, I pull the panel and manually check the heater and defrost thermostat. if one of them is bad, I replace it. If they are both good, replace the board.
If the freezer fan isnt blowing, replace it.