FIXED WRX988SIBM03 Whirlpool Refrigerator Not cooling enough

[dariolopezee]

Model Number

WRX988SIBM03

Brand

Whirlpool

Age

6-10 years

Hi everyone,
I have a Whirlpool Gold Series WRX988SIBM03 refrigerator. About a little over a month ago, we noticed that it stopped making ice. It has done this a few times before, but after fidgeting with the built-in tests and a few resets, it managed to recover on its own. (Never had to do anything to it). One of the other symptoms was that the freezer didn't cool as much as it used to. Neither did the refrigerator portion. When it worked, the freezer would cool down to about 0F. This time, the freezer was hanging out at about 17F. I cleaned the condenser coils and got it down to about 14F with a set point of -5F . Still no ice. The fridge set point is 33F, but it's only getting down to 37F.

Every self test I run shows ok. I opened the back and did some probing on the boards and found the following...
On the power board
P1-1 -> P1-2 = 122VAC
P1-3 -> P1-4 = 122VAC

P2 is weird... The tech sheet that came with the refrigerator says I should have 14VDC from...
P2-1 -> P2-4
P2-2 -> P2-5 &
P2-3 -> P2-6

However, when I look at the board, I have an 8 pin connector, not 6.

If I were to have measured on a 6 pin connector, I would have measured from bottom to top on each column. Doing that on the 8 pin connector I get...
P2-1 -> P2-5 = 14.4VDC
P2-2 -> P2-6 = 14.4VDC
P2-3 -> P2-7 = 14.4VDC
P2-4 -> P2-8 = 14.4VDC
So I'm guessing (someone please confirm) that the power board is fine.
If it matters, here's the part number on the board.
P/N W10665178 has been updated to W10830278

On the control board
P1-1 -> P1-2 = 122VAC
P1-2 -> P1-4 = 122VAC (condenser fan was running)

At this point, I didn't just measure everything and tried to focus on things that sounded like they had something to do with cooling.
P2-3 -> P1-2 = 0VAC (Self test 6 showed bi-metal open). I read somewhere about bypassing the bi-metal, but at this point, I'm not sure how to do that.

P4-1 -> P4-4 = 14.4VDC

P5-1 -> P5-2 = 1.7VDC (connector disconnected). If I connect it, I get something like 0.8VDC (RC thermistor)
P5-3 -> P5-4 = 1.7VDC (disconnected) If I connect it, I get 1VDC (FC thermistor)

P7-1 -< P7-2 = 1.7VDC (disconnected) If I connect it, I get 0.8VDC (Ice Maker thermistor)

Are these measurements supposed to be made with the thermistors loading the circuits?

On the thermistors, I measured the following
RC = 8.2k-ohm with the compartment registering about 37.2F
FC = 12.6k-ohm with the compartment registering about 16.2F
Ice Maker = 9.0k-ohm but I don't have a thermometer on the ice compartment

Based on the tech sheet, it looks like the thermistor resistances are reading in the correct ranges.

I also measured the compressor voltage from P8-7 to P8-8 while it was low and high. Looks okay to me...

Has anything I've presented point to some problem? What other things can I measure to give a clue of the problem?

Sincerely many thanks,
Dario

 

[rickgburton]

With the compressor running, inverter voltage should be 3-6 VDC

 

[Jake]

Rick is absolutely right!

got it down to about 14F with a set point of -5F . Still no ice.

ALSO--->Did you check the frost pattern of the freezer evaporator coil, which is located behind the back panel inside the freezer? Normal would be a thin layer of frost on ALL the coils from Top to Bottom.

Look at the very bottom photo below, which says NORMAL FROST PATTERN.

 

[dariolopezee]

Thank you. I've taken the doors out and there was ice on the back panel. I scraped the ice off the panel and I'm in the process of hair drying the panel to get it off, but it looks like there's a solid chunk of ice on the coils.
Well look at all that ice. What to look at next?

 

[rickgburton]

Self test 6 showed bi-metal open

Replace the bi-metal.

 

[Jake]

Bingo!

Yes, bad bi-metal(defrost thermostat). The defrost thermostat only comes with the evaporator fan motor as a assembly.

Here's the defrost thermostat and evaporator(freezer) fan motor for your model you can order:
W11032800 Motor-Evap


Jake

 

[dariolopezee]

Replaced the bi-metal! Works like a charm! Thank you all!

 

[Jake]

Excellent @dariolopezee Rick has been out sick, hopefully he gets better soon, he will be happy to hear the new defrost thermostat that comes with evaporator(freezer) fan motor fixed it.

Thanks for the update!

Jake