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FIXED Whirlpool Refrigerator WRF736SDAM13 defrost issue - bad switch

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Stevezzz

Premium Member
Joined
Feb 3, 2021
Messages
2
Location
East Coast
Model Number
WRF736SDAM13
Brand
Whirlpool
Age
1-5 years
My Whirlpool WRF736SDAM13 has a bad defrost switch.

I verified this first by reading this forum (and others) to troubleshoot the issue. Using the diagnostics I found that both thermistors are okay ( Service test 1 & 2) , ST 3 & ST 4 okay. Service test 6 shows 02= bi-metal open. Tried ST38 (forced defrost) - no result because bi-metal open. I pulled the freezer back panel and found a totally iced up evaporator. Defrosted with a hair dryer. Pulled wiring harness plug in freezer and measured for continuity for both heater element (30.5 ohms = good) and bi-metal defrost switch (open). I also checked for proper voltages on the main control board. Everything checked out.

Then I cut the defrost thermostat out and put a wire nut on stripped ends of wiring harness. Ran ST 38 again and it DID FORCE a defrost cycle. Removed wire nut and spliced a pig tail extension routed to my freezer compartment so I can do a manual defrost without removing back panel. NOTE: do this ONLY with power disconnected or in Service Test 01 or you will light your day up and maybe fry a circuit. Threw old switch in freezer for 24 hrs, it would not close contacts.

Here is my problem. Whirlpool does not sell a defrost switch alone for this refrigerator. They want to sell a complete wiring harness with evaporator fan, thermistor, defrost switch, etc. which cost over $100. This switch probably costs between $10-30 depending who sells it.

The old switch info is 39TVER31 (type), L50-38F temp range. This means switch open at 50F, close at 12F. I can not find a similar one either online or talking to local appliance shops.

Does anyone know where I can find a similar switch or one with specs fairly close, like L48-30F or similar. I bought one online but it arrived as a L48-15 which means in closes at 33F, which I verified by putting in a cup of ice water. The company I bought it from thought it opened at 48F and closes at 15F, I guess a common misconception.

Thanks.
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
117,051
Location
McMullen Valley, Arizona
There isn't any you can substitute for just the Bi-metal(defrost thermostat).

You are correct, it only comes with the new evaporator fan motor:


Jake
 

Stevezzz

Premium Member
Joined
Feb 3, 2021
Messages
2
Location
East Coast
I found another solution for this issue.

After I found the tech sheet for this refrigerator (found under the right door hinge cover- thanks guys); the spec for the defrost switch is listed as
above 42F°±5° =open and below 12F°±7° =closed. So I searched for a L42-30 switch online and found a guy in Canada selling one used. He indicated the Whirlpool part number is 12001937.

I called the same appliance parts shop who could NOT help me earlier and gave them part number 12001937. They had one in stock and verified that it is a L42-30 switch. I bought it for $41. Installed it and the refrigerator has been running frost free ever since.

The parts store guys typically do not know the specs on a switch since Whirlpool does not list it along with the part number.
Thanks Whirlpool. /s
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
117,051
Location
McMullen Valley, Arizona
That's good to know Steve.(y)

Here's that defrost thermostat(Bi-metal), in case others need it too:
12001937 Thermostat Kit


Thanks for the update!

Jake
 
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