Product review (4 stars): that was my favorite part. The fridge started making this very loud ...
I have a Frigidaire FRT18HB5JW4. The Defrost timer locked up at 2:30 am last Sunday morning, that was my favorite part.
The fridge started making this very loud buzzing noise, could hear it all over the house. Noise was a lot louder when you opened the fridge door. I followed the noise back to inside the fridge compartment inside an access panel next to the light and the thermostat. I removed the old one and looked it up on google. This came up as a replacement. A YouTube video said if the defrost timer stopped working you could manually trigger the timer by using a flat head screw driver to turn the exposed wheel. the gray thing, until it clicked. I did and when I plugged it back into the fridge the buzzing stopped and fridge ran normally. This method got me through the two days until Amazon could ship the replacement to me. Installed in about 30 seconds, no big deal. Hopefully it will out last the 10 year old fridge.

This timer is a shorter duration(6 hours) than the original (10 hours), also the defrost cycle is only 21 minutes rather than 44 minutes. Another reviewer said this didn't seem to effect the fridges operation. I will update if I notice anything.