Hello alt.home.repair -- I'm trying to repair a KitchenAid refrigerator
(freezer on the bottom).
I'm fairly certain the problem is the defrost system. Periodically the
fridge compartment starts to warm up. Cold air comes from the vent in
the freezer section, but little or no air reaches the fridge. It stays
warm until I unplug it and let it sit for a day or two. Then it works
fine for a few months.
The third time this happened, I pulled off the rear panel in the
freezer section. As expected, it was very frosty. It looks like the air
intake in the freezer section is eventually getting plugged. I assume
this is why the fan is unable to blow much air up to the fridge, though
it does circulate air in the freezer.
So... I've tried to isolate the broken part, but they all seem to be
working, at least to the untrained eye. If I manually turn the timer,
the heater comes on. If I then wait 20 or 30 minutes, the heater turns
off and the cooling system starts. To see if the timer was initiating
the defrost cycle I made a tiny wax peak and stood it up on a bit of
aluminum foil next to the heater. Checking it about 10 hours later, the
wax hadn't melted, however it was tipped over in a pool of frozen water
in the bottom of the foil. So something melted the frost.
I'm a bit stumped now. Could one of the parts be working
intermittently? If so, any idea how I would identify it? I could
replace all three, the timer, heater, and thermostat, though it's a bit
more money than I'd like to spend.
Alternatively, perhaps the kids are leaving the door open, and more
frost builds up than the defrost cycle can remove. If the door is left
open very occasionally (say once a month, for 30 or 40 minutes), should
that be enough to overwhelm the defrost cycle?