If you are talking about the cooling fan next to the compressor - this fan must run together with the compressor.
In the situation you described I would recommend to replace this fan. You can not rely on it anymore and it can cause overheating and damage to the compressor.
- The part number for the condenser fan motor is AP2111368
Here are the break down diagrams for the Frigidaire refrigerator Model FRT26XGCD2