How does a refrigerator defrost feature work?

I typically empty & unplug my cottage fridge in late fall and then only use it if I bring enough groceries on winter visits to make it worthwhile. This past weekend I went to "open" my cottage for the season and when I turned the fridge on it didn't start. I fiddled with it a little before unplugging it and using an old Norge in the basement for the weekend.

Sunday I pulled out the fridge and tested the compressor overload...seemed OK. Tested power to it and there was none. Pulled down the thermostat housing & checked that...got continuity there too. Still only a faint hum could be heard when the fridge was plugged in. I took a break and when I returned to it the thing was running and cold inside!

I don't know much about the internals of a refrigerator but all I could come up with to explain this behavior was maybe the unit was unplugged at the start of a defrost cycle, which had to complete before the compressor could get power(?)

Is that how it works? This is an old GE (TBF17PC) that maybe doesn't have an electronic control board. Do old units have a mechanical timer hidden somewhere?

 

Older fridges use a mechanical defrost timer so if it was in defrost mode when it was un-plugged.... it would still be in defrost mode when plugged back in.

I'm pretty sure the timer is down by the compressor on that fridge.

 

I didn't see anything that looked like that but I was only in the back. Maybe it's located behind the smaller front panel. Doesn't really matter--you confirmed it IS a mechanical timer and interrupts the compressor power.

I won't be so quick to grab a meter & screwdriver next time...