Frigidaire freezer cold, refrig in 50's.

Yes pull the refrigerator away from wall and feel top of the compressor. Is it too hot to touch? Are bot fans running. Straight wire the thermostat to see if it is causing this. The start relay and start capacitor may be the reason. Let me know by email you response because Fixya has not been notifying me of any ones response to my solutions. I just found you made a response. Sea Breeze

Because the model FRT21P5A has a manual adjusting vent I believe your problem is either the defrost heater and defrost thermostat and or the cold control (thermostst) is not working correctly. When temperatures rise in the refrigerator side first that is a sign that the air flow from the freezer is restricted. You will need to unplug the refrigerator and remove the rear panel in back of freezer to confirm. If Iced over use a hair dryer to defrost and disconnect one wire on the defrost heater. Check the defrost heater with an ohm meter. You should get a reading. If defective and no reading you need to replace the defrost heater and defrost thermostat. Let me know what you find, Thanks Sea Breeze