Frigidaire Upright Freezer flashing fault code 2

[overmyhead]

Amateur and (so I thought) semi-handy guy attempting to be smart and fix my Frigidaire GLFU2067FW5 freezer.  So far no progress and three shipments of parts.

Have a Frigidaire Gallery Upright that is flashing a fault code of 2 on the control panel about once per second, and occasionally flashing a 0.  Freezer is running cold, between -20 and -25C, with no seeming way to adjust the temperature.

Have replaced the defrost thermostat (297216600), then the Thermistor (297018400), and now the Control Board (216944300).  No change at all in behaviour.

Anyone have any ideas?  My parts bill (including taxes and shipping) is now over $200 - and I'm about ready to ship this thing off to the junk yard!

Thanks very much.

[JWWebster]

Is the thermister up against the evaporator?

[overmyhead]

Thanks for the reply.

The Thermistor is attached (with a screw) to the back wall of the freezer.

The Defrost Thermostat is attached to one of the coils of the ?defrost heater? with a little clip.

[jumptrout51]

The defrost thermostat should attached to the evaporator coil.
Not the heater.
It will terminate the defrost cycle as soon as it comes on.

[overmyhead]

Took a look at the Parts Catalog/Diagram of the unit again - I incorrectly identified the part as the defrost heater.  The defrost Thermostat is attached to the Evaporator coil with a little clip.

[JWWebster]

That thermister must be attached to the coil for proper temp readings. The control board sents out voltage to the sensor. As temps change the resistance changes in the thermister. The control board uses that method to determine the temperature.
Proper positioning of the thermister/sensor is critical. Could be 3 or 4 of these sensors in that ice box.

[overmyhead]

Three or four thermisters....  now that makes sense - so maybe one of the others has failed. 

Time to get out the wire cutters, the multimeter, and the soldering iron (in that order...  and hunt them down and test them individually.

{Of course, when I changed the thermister and it didn't fix the problem, I threw the old one out - so I still may have a parts order to do if one of them has failed.

Thanks for your help.  Will let you know the outcome!

[JWWebster]

Topsloshers shortcuts

[overmyhead]

Thanks for link - Electronic Controled Freezer 5995482584 was the key (filename: 472_ElectronicControledFreezerServiceManual.pdf)

from Page 50 - Section G - Troubleshooting Chart (Deluxe Electronic Control model)
 - symptom - user interface display is blank.

I detached user interface module from the door and measured the voltage between the brown and orange wires in the plug - was essentially zero (25mV - i.e. open)

Got to back of Freezer, found Electronic Control module, and detached 4-pin plug.   Measured voltage between red wire and black wire (4.95VDC)

Looks like I've got an open connection between the User Interface display and the Electronic Control Module.  May see if I can breadboard up a header to connect the two together directly to verify.

Also, page 5-7 (45) of "707_Upright_Freezer_with_Standard_and_Electronic_Controls_5995531505.pdf" appears to be my unit - that is how the thermistor and defrost thermostat were arranged, with the thermistor attached to the back wall of the freezer compartment behind the evaporator cover.

The schematic on the back of my unit shows only one thermistor - do they generally show only one even if multiples?  

Thanks again for the link...

[overmyhead]

Confirmed - bad wiring harness between the Electronic Control Module and the User Interface Display.

[JWWebster]

Wow Cool. I love it when a plan comes together.

[JWWebster]