Whirlpool WRF736SDAM13 Evaporator Defrost System Repair!

Shop Fridge WRF736SDAM13 Defrost Repair… (Quick and Dirty)

I guess these Whirlpool units seem to have major issues with their defrost system and their main control board Part # WPW10589838 $300 or more from reputable sources you do get $60.00 back for returning your board.

From reading blogs the Evaporator Fan (Includes Harness, Thermistor, & Defrost Thermostat.

I arrived home and guess what the evaporator fan was making Noise..

Guess What, The Evaporator was Iced Up..

On this refrigerator the Evaporator Fan assembly was replace Sept. 2018.

Doing the Service Test Diagnostics.. It looked like the Bi-Metal Defrost Thermostat Staying Open.. I Defrosted the System and Removed the Evaporator Assembly and Bench Checked it. The Bi-Metal Defrost Thermostat was 56K Ohm and Closed When it was Cold? The Defrost Heating Element was 30 Ohm.

So I Reinstalled and Let Refrigerator Get Cold, I repeated Service Test 6 Returned 02 that Said it was Bi-Metal Defrost Thermostat was Open the Coils were Frosted and Cold so that had to be Wrong..

I Pulled The Back Cover Where the Main Board and PSU is Housed, I Hooked My Multi Meter Up to The The Main Board (Bottom Board) Connector P2 Pin 3 (Brown Wire) and Pin 7 (Pink Wire) which is where the Defrost Thermostat is on the PCB. I was showing that the Bi-Metal Defrost Thermostat was indeed closed.. I Checked for Voltage Nada.. Darn it’s the Overly Priced Main Control Board.. Lets Diagnose It..

Pulled The Board.. To Trace Out The Defrost Circuit For Diagnostics.
(Yes Relay K7 is Missing Explain Below)

I have seen this brand low cost and low quality relay in the past on other electronics so I trace the circuit out and pull the relay K6 for a bench check. Yep Houston thats the problem! I Pulled Relay K7 as it is the same relay I swapped it over to K6 and Reinstalled main board and Did Service Test 6 Again we got an 01 meaning that the Bi-Metal Defrost Thermostat was Closed I Disconnected the Defrost Thermostat let it get Warm it and Went to 02 (Open) Yep working as it should.

So my temporary solution was to Keep Relay K7 (RC/FC Door Open Circuit) out witch will Temporarily disable the Door Switches The Relay Is Normally Open When Door is Closed so it should not be an issue just no Lights and fans will run when doors are open.

I will order a set of new HF33F-012-ZS Relays form Arrow $7.00 + Shipping. One can alternatively get 10 of them from Feebay out of china for about 5.00 shipped LOL.

I wired up a temp general purposes relay so when doors open it turns on the lights. 4 Days Later The Refrigerator Defrost System Seems to be working as it should. Waiting on My Relays From China!

So My Symptoms:

All Service Tests Passed and Showed The Bi-Metal Defrost Thermostat was Staying Open when it was for sure Closed.

This fix involves Desoldering and Soldering of a double sided lead free PCB with a large ground plane if you do not know how to do it or do not have the proper tools refer to a professional.

May 2021 Update Year and a Half Later No Issues..