FIXED Subzero refrigerator/freezers 700TCI- Ice buildup

[georgepb]

I just opened the evap cover and saw new ice build-up. Will upload pics shortly. So this is 12 hours after I restarted
the unit with the theminster disconnected.

 

[georgepb]

Pics of evap bay, left to right.

 

[georgepb]

Does this look too much ice buildup to you with auto 6-hour/20min defrost cycle on?

 

[georgepb]

If the drain heater is always on there shouldn't be any frost around it right?

 

[paulhl]

Right, you can check for 120v to it. Is that fan behind the evap running?

 

[georgepb]

Yes, the fan has been running. I just removed the terminator, put it in a freezer for 20min and checked the continuity. It
is still open.

 

[georgepb]

Speaking of the fan, it should stop during defrost cycle right? Otherwise the melting water would be blown toward the wall
which could explain the frost builtup on the wall above the drain hole (see one of the pics above)?

 

[georgepb]

Hi, does anyone know the part # of this thermister and where it's located? I can't find it on the parts list/sysstem diagram, only
saw the other two thermisters which share the same part # of 4323800. From this diagram it looks like part of the upper
freezer drawer door switch (part # 4202580). Thanks.

 

[paulhl]

It is and comes with the switch.

 

[georgepb]

Thanks for confirming it. Just an update, it's been about 10 days since the unit was restarted with the evap thermister removed. The temperature was running normal most of the time. I even stuck a thermometer into the fridge and recorded the temperature over a 24 hours period. I could clearly see the fridge temperature tick up a few degree every six hours then moving back down to 37 degree. I guess this is the forced defrost cycle. But these defrost cycles did not melt any ice into
the drain pan.

I also restarted the unit twice during this period and each restart resulted in a large pool of water in the drain pan. So in short the fridge is working more or less and there is urgent need to do anything drastic. But when I get a chance and have the parts ready, I am thinking of replacing all the thermisters and the control board. I've had enough fun with this fridge and learned a ton. Thanks again for your help. Will make another donation shortly.

 

[georgepb]

No urgent need.... lol

 

[georgepb]

Does this control board need to be configured/programmed somehow before it can be used?
I just got it and it looks identical to the one I have. But when I put it in I got slightly different
messages on display. My old one has two zones: cabinet and upper/lower freezer drawers.
The new board has three: cabinet, upper freezer drawer, and lower freezer drawer. Not only that,
for the freezer settings I am unable to lower it below 31 degrees no matter how many times
I pressed the colder buttom.

 

[paulhl]

When you first installed it did you get double dash's in display? What was part# Should be 4201992 and it is mod# specific

 

[georgepb]

No I did not get any double dash's and it just worked with normal temperature displays for three zones instead of two. When I toggled through each zone and used the warmer/colder keys to set the temperatures for the freezer zones they wouldn't go lower than 31 degree. Yes the part # is 4201992. They looked identical when places side by side.
I did noticed for the chip in the middle left which I believe stores the firmware, the new board is completely black
while my old one has a white tag on it with bunch of numbers on it.

 

[paulhl]

Like I said that board is mod# specific and does not need programing. Try pressing alarm & unit on/off(15 secs). For other boards this puts you in manual config mode and the mod# will show in the display.

 

[georgepb]

Okay. I will try it. Thanks.

 

[georgepb]

my unit has no on/off button.

 

[paulhl]

Well those instructions were for a programable board, you either received the wrong board or it's defective. Where did you buy it?

 

[georgepb]

I got it on eBay but it came in original Subzero packaging, minus the single-page instructions which normally
accompany these boards.

 

[georgepb]

And I bought a 3-year insurance so if it is defective I'm fully covered.