Two days ago my Frigidaire side by side began making a buzzing sound for approximately 15 secs every 10-15 minutes or so. I pulled it away from wall and removed the back cover to determine the location of the sound. It appeared to be coming from the compressor. The compressor felt a bit hot yet the cooling fan was running fine. I Googled the symptoms and there seems to have been quite a few people with this same problem but no definite solution. One solution was to replace the compressor start relay so on a hunch I unplugged and removed both the relay and capacitor and checked for any signs of damage. All looked good so I reinstalled them, plugged the fridge back in and to my amazement the fridge began working again with no buzzing. Unfortunately yesterday it began acting up again and the food in the freezer started to melt. I again unplugged the fridge,removed the starter relay and capacitor replugged everything back in but this time the buzzing did not go away. I turned the freezer thermostat off and the buzzing stopped. Since I had already removed all the food from the freezer section I left the freezer thermostat off and the fridge thermostat on overnight. This morning when I turned the freezer thermostat back to normal all seems well again. 
Hello, Randy.
If you are absolutely sure that the buzzing sound is coming from the compressor, then I suggest you replace the start relay and overload.
The start devise [PART]AP3837323 [/PART]
Here are the breakdown diagrams and Replacement parts for Frigidaire FRS3R4EB0 Frigidaire/refrigerator | AppliancePartsPros.com
How can I be sure when the problem randomly corrects itself?
Is there a way to test? I have a Fluke meter.
You probably have a busted start waifer inside the start device. If it rattles when shaken, it’s bad. To confirm, measure the resistance between the bottom two compressor pins in the start device, should be between 5 and 10 ohms.
Hey Richappy, Your right.
When I shake the start relay (pictured above) there is a distinct rattling sound. This may explain why it suddenly started working again after I removed it to check for any external signs of failure such as overheating.Even though it is now working again I am going to order a new part. Then for educational purposes and my own curiosity, I am going to dissect the old part by drilling out the rivet with a small bit. It looks like it can easily be opened after doing so.
I will post pictures. This may help others (including myself) to understand the workings of these devises.
Thanks for the help.Rich/Simon
To prevent problems, put a surge protector in the wall outlet, I use a Belkin
F9H120-CW from Amazon.
How do you get the relay out? It has a red and blue wire and I can’t get it out. I shake it and I don’t hear any rattle. I have the same symptons as the original poster. I have a Frigidaire GLRS267ZAW4.
I tested the capacitor for continuity and I don’t get any reading. I stuck the pins in the relay (the three holes where it plugs in to the compressor) and they all had continuity. Think my prob is the capacitor?
Thanks!