KitchenAid KORU06RSSS refrigerator Bi-Metal Defrost switch help

[BCA]

Hello,

My KitchenAid under-counter refrigerator model # KORU06RSSS stopped cooling and I found that the bimetal switch on the evaporator coil had failed. It was visibly blown out.

The replacement part has been discontinued by Whirlpool (#2303775) and I haven't been able to locate one. The numbers on the original one are:

T-O-D  37TV32  31634  F36-18F

2303775  J0504

From my research (please tell if I'm wrong) it is a close on temperature rise design that closes at 36° and opens at 18°. 

I did find one that closes at 50° and opens at 35° and after installing it the fridge has been working again for about a week now, but is only cooling beverages to 50° which I kind of expected but I mainly wanted to try it as a test to see if there were any other issues besides the failed bimetal switch. 

There is a seller that claims to have a replacement but the numbers on it are L64-41F. Does the L in front of the higher number mean something different than the F?

Any help finding an original replacement or one that is much closer to the original that would be compatible would be much appreciated. 

 

Thank you,

Brent

 

 

[Budget Appliance Repair]

F36-18 (opens at 36 degrees and closes at 18 degrees, the number after the dash isn't the temp that it closes but the differential temp from the open temp 36 degree open temp minus the differential temp of 18 degrees equals closes at 18 degrees).

The F50-35 would open at 50 degrees and close at 15 degrees
The L64-41 would open at 64 degrees and close at 23 degrees

It sounds like you have a problem with the sealed system, (low on refrigerant), if it will only get down to 50 degrees as the defrost t-stat only comes into play when it goes into a defrost every 6 to 8 hours - the higher open temps would let it get too warm during defrost periods but not make it only be able to get down to 50 degrees in between defrost cycles.

I use a Frigidaire part# 297216600 (N42-21) for a general replacement in a lot of full size top mount Whirlpools.  This would be a better replacement for what you need then what you already put in.  You definitely don't want to put the L64-41 in there.  This being such a small box letting the evaporator defrost temp get up to 50 or 64 degrees before turning off defrost is really pushing it.

[BCA]

Hi Willie,

The original one that failed is labeled 37TV32 and from what I read in this pdf, 

https://www.copeland.com/documents/37t-prodcut-bulletin-en-us-1572428.pdf  

the 32 means that it closes the circuit on temperature rise and if it ended in 31 it would open on the temperature rise. From what I am seeing, the Frigidaire part that you referenced does the opposite of what my original did. 

Can you confirm?

 

Thanks,

Brent

 

 

[Budget Appliance Repair]

9 hours ago, BCA said:

the 32 means that it closes the circuit on temperature rise and if it ended in 31 it would open on the temperature rise.

Absolutely NO - The 37TV32 on the part has nothing at all to do with the temps that it operates at, (you need to go back and read that page you linked to a little better).  37T is the type, (means the 7/8" diameter type)

V – Low load resistive
applications, using
conical contacts

3 – Tube mounting

Last number
1 – SPST, open on
temperature rise
2 – SPST, close on
temperature rise

Don't know if you wrote/copied the last number wrong or it's backwards, but all defrost terminator t-stats open when the temp raises to a high point to turn off the defrost heater before the evaporator area turns into an oven, (gets too hot).

The original defrost terminator t-stat specs of F36-18F, the first number is open/highest temp you want the evaporator area to get to = 36 degrees and the second number is the differential close temp first number minus differential = temp at which the switch should close.

[tstebbins]

Just to but in here , all do not open to turn off a heater. checking his model number this unit does not have a heater in it. There are a few out there that are in line with the compressor, so when the evaporator reaches that 18 degree mark it will in fact open and shut down the compressor. When it warms back up will allow the compressor to restart. 

Older GE built in all refrigerators have a similar design with the thermostat wired in series with the compressor.

[Budget Appliance Repair]

@tstebbins I think you are very mistaken in what you say above.

I've been doing appliance work for 38 years now and have never heard of a defrost t-stat that turns off a compressor - the compressors do have an overload protector that will shut down the compressor if it is drawing too high of an AMP load for too long or if the compressor gets too hot.

Some of the older Amana's and maybe some of the GE's have the evaporator fan wired thru the defrost t-stat so the evaporator fan won't turn back on until the defrost t-stat closes, (gets cold enough), so it doesn't start blowing air until the evaporator is good and cold again.

EDITED TO ADD: looked for a wiring diagram part# 2311029 - can't find one, but found there are two bi-metals in this unit and @tstebbins you are correct - no defrost heater, (This being just a small under counter refrigerator most likely just an off cycle defrost and maybe just doesn't turn the evaporator fan back on until the evaporator is back down to 18 degrees and turns the evaporator fan off when the evaporator temp is above 36 degrees so as not to be circulating air until the evaporator is in the correct temp range.

The second bi-metal in this system is listed as "Bi-metal, Liner Heater" - I don't see any liner heater listed in the parts list, (it may be a non serviceable part in the liner to keep the outer cabinet from sweating since this unit is made to be built-in to a cabinet area it appears.

Edited October 28, 2023 by Budget Appliance Repair

[Captain Dunsel]

Here is what the 2311029 says in a screen shot:

[Budget Appliance Repair]

@Captain Dunsel WOW,  That's a new one for me  - never seen a setup like this before.

So the defrost bi-metal does cut the power to the compressor and it does seem it would have to be opposite of a normal defrost bi-metal, (closes at 36 degrees or warmer to make sure the compress runs if the evaporator temp is above 36 degrees and opens when the evaporator is 18 degrees as to not get to cold and freeze food in this small refrigerator - even though it seems the cold control should turn off the compressor before the refrigerator becomes a freezer.

Hmmm, interesting setup.

[tstebbins]

yes, that is it in a nut shell. some of the all refrigerator built in GE have that set up, the old ones that is. it is odd but they are out there lol

 

[tstebbins]

oh, and the thermostat is set up that way to ensure the coils are fully defrosted i think not to keep from getting to cold. 

[Terry Carmen]

FWIW, "open on temperature drop" is common on dehumidifiers, commercial coolers and used to be sort of common on single-door refrigerators that shared a single evaporator between the refrigerator and freezer.

It defrosts the evaporator then re-enables the compressor,

[Rich Armstrong]

What are the two “ambient” heaters is series with a bi-metal in front? Does the evaporator have two defrost t-stats? 

[tstebbins]

om that one it is actually on the discharge of the compressor, used to turn the heaters on when closed. this is mainly an out door unit i think

 

[Budget Appliance Repair]

2 hours ago, tstebbins said:

this is mainly an out door unit i think

It is an out door unit - found this info in the install instructions - Not seeing any heaters listed on the parts diagram, I thought maybe a non-replaceable heater in the cabinet to keep cabinet from sweating maybe?

[Econo Appliance]

16 hours ago, Budget Appliance Repair said:

Not seeing any heaters listed on the parts diagram, I thought maybe a non-replaceable heater in the cabinet to keep cabinet from sweating maybe?

Foamed in place, i would guess its in the liner.   

In my garage refrigerator, 1990 whirlpool sxs, the freezer will warm up on cold 30° nights. With the thermostat capillary on the fridge side, it gets satisfied by cold ambient temperatures, compressor goes idle,  the freezer creeps up to ref temps. If I had liner heaters activated by the thermostat  in this thread, theoretically it would take care of my "problem."

   I know its been cold in my garage when my ice cubes are melted and refrozen.

Edited November 4, 2023 by Econo Appliance

[tstebbins]

lol, yes these are in the liner