Kitchen Large Electric Appliances - frigidare side by side

Friend has a frigidare side by side about 4 yrs old. She says once or twice a week it will stop being cold, the freezer starts th thaw and opening door to fridge you can hear it running but it is not cold. It has an in door ice and water dispenser. Repairman replaced valve in water dispenser line.
I told her it might have leak in freon line ro compressor is going bad. repairman said he needs to contact frigidare to ask what problem could be.

Any ideas?

Back of fridge is clean and there is space so it has circulation. That was the first thing I mentioned but that is not the problem.

thanks for any help

jimco