Frigidare freezer making buzzing sound like a motor

SOURCE: Frigidaire Refrigerator-Freezer noise problem

you can replace the part

SOURCE: frigidaire refrigerator model FRT21LRGW5-compressor sound is loud

Sounds like the start relay or start capacitor has failed.

Unplug the unit until you can get a replacement or the compressor will be ruined (if it's not already.).

PTC start relay is P/N 218721108 $36.49
Capacitor is P/N 218909901 $7.99

P/N and pricing from Sears Parts.

SOURCE: Frigidaire side-by-side model # FRS26H5ASB4 making humming or buzzing noise

I had the same problem. I found the buzzing noise was caused by ice build up around the fan motor inside the freezer. I believe water must have leaked down around the fan during a defrost cycle. I removed the ice maker, the ice cube bin and ice dispenser auger motor. It sounds complicated, but it isn't too bad. The ice maker and auger are connected with quick connect plugs. So just unplug, remove the screws and remove them from the freezer. You will need to remove several other screws as well, I believe 11 in total as well as the top freezer rack. This will give you access to the white aluminum panel that runs from the top of the freezer to about halfway down the back of the freezer. After you remove the aluminum panel you will see the fan about half way down the freezer. I found a lot of ice around my fan. The fan blades were hitting the ice causing the buzz. Remove the ice and the buzzing is gone. It took me an hour to complete this repair. I hope this helps.

SOURCE: Frigidaire Side-by-side not cooling or freezing

Dear customer,

We suggest u to do the follwoing checks,

1. Hissing and popping is normal on frost free refrigerators, it is the defrost heater
   
2. Check that the refrigerator is level
   
3. Check the drain pan
   
4. Check the condensor fan
   
5. Check the evaporator fan
   
6. Inspect the compressor mounts

SOURCE: Frigidaire Frig side by side making a loud buzzing noise

it sounds like the compressor, or something near it. it is generally the only moving part in a refrigerator other than the door, so would be my first guess. If it is constantly running, but staying cool in the freezer there may be a small leak somewhere or the compressor is losing power, and pumping slower.