FIXED Subzero refrigerator/freezers 700TCI- Ice buildup

[paulhl]

Just unplug it. If you have access to an amp meter time the length of the defrost

 

[georgepb]

where is the thermistor located, behind the back panel?

 

[paulhl]

On r/s of evap a few inches down

 

[georgepb]

got it. thanks.

 

[paulhl]

By time the defrost I mean the time the heater is on, not the time until compressor kicks in which should be 20 minutes with thermistor disc'd

 

[georgepb]

when the heater is on are all the heaters on at the same time and for the same duration? evap heater, drain heater, air duct heater, etc.

 

[paulhl]

No, only the defrost & duct heater are controlled by terminator or end of cycle. Drain & fill tube heaters powered all the time. Should see a little over 6 amps in defrost

 

[georgepb]

got it. thanks.

 

[georgepb]

Just to confirm, this is the sensor I should disconnect to force a 6-hour/20-min defrost cycle?

 

[paulhl]

Yeah but that terminator is way too close to the heater, it belongs above the thermistor near the top of the evap

 

[georgepb]

I'll check. It could be the camera angle making them look closer than they are. I'll disconnect the plug with two black wires.

 

[georgepb]

I think you are right Paul. I checked the service manual and the terminator (part #39) is located above the thermister (part #35)
near the top of the evap. Should I reposition the terminator and see if it fixes the problem before disconnecting the sensor?

 

[georgepb]

Correction: part #41 terminator and #40 thermistor

 

[paulhl]

Absolutely, very top of evap

 

[georgepb]

Here is a picture from a different angle. I only have two choices and they both seem still pretty close to the heater?

 

[georgepb]

In this replaement part the terminator seems to be attached to the same place as mine.

 

[georgepb]

It's very hard to unplug the evap thermister without removing the back panel and it's much easier to open the overhead
control board instead. So I opened the control board and removed pin #1 of plug P1. I believe this should disconnect the
thermister from the system. We'll see how it goes in a day or two.

 

[paulhl]

Pin 1&2 are spare-7&8(blacks) go to evap thermistor. Indeed the terminator is at that location, I have an evap from a TFI and it's there also but not as close as your pic. If you can look up a 4201910 and see where they show the terminator, that's not where the one on mine is?

 

[georgepb]

Here is a better close-up of the diagram. Evap sensor (therminster) is the only component that uses light blue with black strand wire and
it's connected to the side of the board with only one connector. I'll check the evap bay shortly to see if there is any ice buildup. If there
still is I plan to short the terminator and watch it closely for a day. Now I'm looking at this picture closely I think we were both right.
My pin 1-2 is your pin 7-8, I simply counted the pin #'s in the wrong direction.

 

[paulhl]

Yes usually all their thermistors have a blue tracer, you'll see the others are blue/white & blue yellow. There should be a box to the right of that wiring diagram with all pins and color codes. Why short the terminator?