Hello,
I seem to be having some cooling issues with my kenmore 596.58695890. Last year the evaporator fan wasn’t working, no power, so I had to replace the control for that. Now I’ve noticed it’s not quite getting cold enough, some things are thawed a bit. Sometimes it’s plenty cold, sometimes it’s not.
I removed the back panel, and the top half was frosted but not the bottom. Fan wasn’t running, closed it for a minute, walked away and the fan was running. Did a manual advance to defrost mode and that kicked in and definitely works as it heated up the coils and defrosted them completely.
Advanced it again so it should be cooling, but the evaporator fan isn’t running again. I’m not sure if that should always be running, or if it just runs at certain times during cooling mode. I know it was working earlier, just doesn’t seem to run all the time, so not sure if that’s my problem again.
As a followup to this I did test for power at the 2 leads going to the motor that controls the fan. All I have is a cheapo tester, same I used last year, that shows AC110V and AC220V. I believe last year it showed power to here when the motor was bad.
This time I’m not showing anything at those 2 leads, but the fan was definitely running earlier in the day. Reading in some of the forums this sounds like it might be something to do with the defrost thermostat maybe? But not sure how to test that.
And now the fan is running again, about an hour and a half after it’s been in cooling mode and the freezer being up around 45 degrees at the very top. So, I think I’m going to order a new defrost thermostat sometime this weekend, but if someone wants to chime in to confirm my suspicions that would be great 
A partially frosted evaporator coil is usually an indication of a refrigerant leak or a partial restriction. You may want to check the defrost timer.
It’s fully frosted now and the fan is still running. The timer on the bottom is definitely moving around so once it goes back to defrost mode and then back to cooling mode I’ll see if the fan kicks on. It just seems like what’s happening is that fan isn’t kicking back on until the freezer gets much too warm.
This may be loose connections at the fan or the defrost timer; or a bad defrost timer.