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Kitchenaid KSSC42QMS00 freezer fine, fridge warm, many parts replaced

dberg1

Premium Member
Joined
Sep 4, 2009
Messages
2
Location
Delaware
Freezer set to 0 degrees, display reads 0, digital thermometer placed in freezer with external monitor reads 0. Freezer set to -5, display reads -5, digital thermometer reads -5. If fridge set 35, display reads 35, digital thermometer reads 47. Set at 38, display shows 38, digital thermometer reads 49. Food going bad at those temps. At max cool setting still can't get below 45.

When it worked fine, the bottom vegetable drawer used to freeze lettuce occassionally. Hasn't done that is a long time. Having milk in door sour way too soon so I'm not imaging a problem.

Compressor and condenser run fine, no dust on condenser coils.

I have had two repair folks out and, so far, I've replaced the following parts: main circuit board, inverter box, refrigerator thermistor, air baffle/diffuser. Still same problem. Removed evaporator cover. Looks fine, no uneven ice problem, not blocked with ice at all, just the fine layer you would expect with a properly working evaporator. Evaporator fan working fine. You can feel air flowing into fridge through diffuser.

Repair manual says the display won't show temperature differences between set and actual temps if the difference is less than 6 degrees (to account for temp changes caused by door opening/closing). But there's a difference of more than 10 degrees which isn't being reflected in the display.

Does the display board control how the evaporator fan and diffuser run or is that done by the main board which was already replaced? Why doesn't the display board show a 10-12 degree temperature difference between set and actual? When unplugged and plugged back in after a 1/2 hour, it did reflect a 20-25 degree difference, but I didn't watch to see at what point it went to display temp. Which logic board is responsible for the monitoring of set vs actual? Main circuit board or display circuit board? If the display circuit board, does the display board then send signal to main board to turn on compressor, evaporator, evaporator fan, diffuser, etc.? Just trying to figure out whether to spend another $150 to replace display board.

Any ideas on what to try now?
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
121,854
Location
McMullen Valley, Arizona
Hi,

I've never worked on this model before, I'll ask TechnicianBrian if he may know what maybe the cause.


Jake
 

TechnicianBrian

Appliance Tech
Joined
Nov 16, 2007
Messages
349
Location
Portland, OR
Just a few thoughts. The main board does everything on that model as the display board is simply just that. I understand your concern over why the display does not seem to update correctly, but I would be more interested in what the unit is actually doing. Meaning, if it is not cold enough in the fresh food section, is the compressor still running or is it shutting off because the board thinks it is cold enough? The main board is primarily interested in keeping the freezer section cold and does this by cycling the compressor. The fresh food section is kept cool by the airflow from the evaporator fan and cycling the air diffuser. So if it is warmer than expected in the fresh food section and the diffuser should be open and the evaporator fan should be on. If everything seems to running, but it is still not cold enough, then an airflow issue would be a likely place to look. For example, you may feel air coming in from the diffuser when the freezer door is open, but then it slows once it is closed. This would indicate the air return from the bottom of the fresh food section to the freezer section are restricted by frost. This will also be the cause of items freezing in the crispers because the air is slowed and pools near the bottom of the compartment. This continues until the returns become more blocked, then cold air cannot circulate from the freezer to the fresh food section resulting in a temperature rise but everything seems to be running. So I guess my suggestion is to look at the airflow between the two sides, and concentrate on what is working, or not working and ignore the display settings. You already replaced the main board and thermistors so unless one of them was bad (not likely) then we must assume they are working and begin with the basics to find the source of the problem. Hope this helps.
 

dberg1

Premium Member
Joined
Sep 4, 2009
Messages
2
Location
Delaware
Thanks for your suggestions. I removed the evaporator cover and verified again that there is no blockage of the return air from the fridge.

I also re-verified that there is no diffuser blockage and that the diffuser door is fully open.

If the evaporator fan is working, how likely or unlikely would the fan still not be able to operate at full speed (especially if it passed the on-board diagnostic test). How strong a flow should I feel when holding my hand at diffuser? I can feel air being blown in, but it isn't real strong, more like a very gentle flow.

I've been monitoring temps in fridge. In last several days, at max cool setting (34 degrees), I'm getting 45-48 degrees on the top shelf, 37-39 degrees on shelf where thermistor is (which may explain why display reflects set temp), 38-40 degrees next shelf down, 38-50 at the door bottom shelf. I haven't checked meat drawer or lower two drawers recently, but the lower two drawers also were warm before this last testing. Are these wide variations in temperature to be expected and considered normal? If so, why are things like milk souring when then didn't use to a year ago? Fridge is only four years old.

Thanks for your help.
 

TechnicianBrian

Appliance Tech
Joined
Nov 16, 2007
Messages
349
Location
Portland, OR
This still sounds like an airflow problem since cold air is denser and falls, it should be coldest at the bottom and get progressivly warmer as you go up in the cavity. The airflow from the diffuser will not be very fast so if you feel air moving, then it should be OK, but without seeing it in person I cannot be positive that it isn't running slow. Also, remove the top grill and verify the condenser fan is moving and make sure the lights are turning off in the fresh food section when the door is closed. But if you have the evaporator with a full frost pattern, the fan is turning, and the diffuser is open, then it should be cold as long as the air is circulating from the freezer up top, and returning down at the bottom. With an open diffuser, that tells me the control is trying to keep things cool, but the temperature increase as you get lower doesn't seem right.
 
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