Whirlpool Fridge WRS588FIHW00 evap freezing up

[whrlpl]

This is 2 year old fridge. The evaporator started freezing up - and the fridge became warm.

Without any direct troubleshooting - I changed out the bimetal evap temp sensor with the OEM replacement part WPW10225581.

5 days later, the evap was frozen up again. I realized I needed to do more troubleshooting - so - I tested the old bimetal evap temp sensor and the new bimetal evap temp sensor. Both tested good (cold temp closed, warm temp open). So - it shouldn't have been the temp sensor. This time - I checked the heater element/cord - and it was good (basically zero impedence end to end). I also discovered the service diagnostic mode worksheet (W11090558 - which has a test to check the bimetal  temp sensor. When I run it ... test#6 (Defrost heater/bi-metal test)... it shows a result of "02" ... which means open. I have repeated test#6 multiple times for 2 weeks with the fridge running - and it always shows open. However, for 2 weeks the evap has NOT frozen up - and the fridge is working correctly. So - the system thinks the evap bimetal sensor is open (evaporator is warm), but the evaporator looks like it is correctly defrosting. Something doesn't add up because if the bimetal evap temp sensor is open, it prevents the defrost cycle from operating.

So, the fridge appears to be working after 2 weeks. I can't explain why it wasn't working. With  test#6 failing, I can't explain why the fridge is working. Does anyone have experience with service diagnostic mode # 6 on the whirlpool?

thx

[Josh Smith]

Sounds like a board problem, when you shut off power to do your test, maybe the restart put the board back on track. They do weird things sometimes..........

[CrazyCarl]

Model number?

[Vance R]

Have gotten off results from test 6. Check the bimetal and heater circuits from the board. Unplug the refrig from power, then remove connector P2 and ohm pin 3 (brn wire) to pin 7 (pk wire) - 56k ohms means bimetal is open, 0 ohm means bimetal is closed. Next ohm Connector P2 pin 7 (pk wire) to connector P1 pin 2 (wh wire) - If bi metal is closed the circuit should ohm  be 441 to 488 ohms as per specs, if bimetal is open it should be the 56k ohms.