Repair and disassembly guides for food cooling appliances including refrigerators, freezers and fridge-freezers.

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GE Monogram Refrigerator Freezing Up

Model number is ZISS420DMCS

My 14 year-old GE Monogram side-by-side (built-in) refrigerator is not cooling properly on the fridge side. I have it set to 40 degrees, but it gets down to 31 degrees and is freezing the food.

I replaced two thermistors, but that did not resolve the issue. I am thinking perhaps the thermostat/temp control unit?

Unfortunately, I cannot find any manuals or videos pertaining to my particular model, so disassembly is tedious.

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Hi @cruiseman ,

What is the model number of your fridge?

Have you checked that the damper from the freezer to the fridge is not stuck in the open position, allowing the freezer air to travel into the fridge?

It should do this normally but when the set temp is reached in the fridge it should close off, preventing further cold air entering


Model number is ZISS420DMCS

I removed the upper panel to check the damper unit, and I cannot find it. What is really weird, is when I replaced the panel (4 screws), closed the door and re-opened the door, now the 2 halogen lights are out! I looked at the wires and they are fine.

As you can see in the photo on the original post, all my lights are working, even the back light and the 2 halogens are not working now.

Not sure where the damper assy is. I took a photo and will try to post it to my original question.

UPDATE: Just checked the fridge again, and the lights are working. Maybe there is a temperature shut-off?



Hi @cruiseman ,

There is a air damper part #367 shown in the fresh food section diagram

here is a link to the spare parts for your fridge.

In the 'fridge section (shown in the freezer exploded view diagram) it shows a rear duct (part #733) but that is all and a couple of baffles around the evap unit.


There is also this which may be of some help, unless this is the one you 'd already changed



I removed the silicone holding the Styrofoam "box" around the damper unit so I could see the damper. When I removed the foam box, the damper door was CLOSED. I turned the temp down to 40, closed the door and in a few seconds, checked again, and the damper was OPEN. This indicates to me that the damper door is functioning, at least the door mech is not frozen open.

I am a little stumped at this point. Something must be keeping the damper door open.


Hi @cruiseman ,

Try placing a thermometer in the fridge at the bottom (and the freezer if you have that many) to verify that the temperature indicated by the control panel, when viewing the actual temp, is what is actually in the fridge (freezer) within a degree or so anyway

Wondering if the control board is out and therefore thinking that it is warmer than it actually is. With the freezer it wouldn't be so noticeable as you mightn't be able to physically distinguish between 5F or 0F, whereas between 37F and 32F in the fridge you would if you get my drift

You've replaced the thermistors so I'm assuming that they are sending the correct resistance reading (relative to the temp) to the control unit, but maybe the problem is there.

Does the compressor run continuously? It may be a bit hard to know, what with normal activity of the doors opening and closing and cold is lost from the fridge. Check first thing in the a.m. as the fridge has had all night to get to the correct temp, so the compressor shouldn't be running trying to get it colder (unless an auto defrost has just finished and it is trying to get the freezer cold again)


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Cause 1

The Evaporator Coils are Frosted Over

The defrost heater assembly turns on a few times throughout the day to melt away any frost that may have accumulated on the evaporator coils. If the defrost heater assembly is defective, frost will continue to accumulate on the evaporator coils, and the coils will become plugged with frost. If the evaporator coils are frosted over, the airflow through the coils will be restricted, causing the refrigerator not to cool. Check the evaporator coils to determine if they are frosted over. If the evaporator coils are frosted over, test each component of the defrost system.

Cause 2

Evaporator Fan Motor

The evaporator fan motor draws cold air over the evaporator coils and circulates it throughout the freezer. If the evaporator fan is not working, the freezer or refrigerator will not cool adequately. To determine if the evaporator fan motor is defective, try turning the fan blade by hand. If the fan blade does not turn freely, replace the fan motor. Additionally, if the motor is unusually noisy, replace it. Finally, if the motor does not run at all, use a multimeter to test the motor windings for continuity. If the windings do not have continuity, replace the evaporator fan motor..

Cause 3

Damper Control Assembly

The air damper control opens and closes to let the proper amount of cold air into the refrigerator compartment. If the damper does not open properly, it won’t let enough cold air into the refrigerator. Check the damper control to determine if it is broken or stuck closed.

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Hello chris, did you repaired your monogram?


Yes. Replaced the Air Handler Assembly in the bottom of the fridge and that solved the problem


I’m glad you found the problem and everything is working. Take care


What’s the air handler assembly? I have the same fridge with the exact same problem. Is it the damper assembly? U said it’s “in the bottom of the fridge?” I don’t have anything mechanical in the bottom of my fridge cabinet.



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