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Sub Zero 642/S3 Serial M2679264: No power to fridge compressor, Freezer not at temp

6 posts in this topic

This 642 has temps around 18f at freezer and 45f + at FFside.  The compressor for the freezer runs fine, the compressor for the FF is cold and there is not 120vac at the wires to the relay.


The display says 'Service' and there is a EC on the right of the display where the temp should be for the FF section.


I found the control board test sheet and ran all the test listed, seems I got 120vac at every test that I was supposed to get 120vac.


I couldn't get any other error codes other than EC and service to show up on the display. Are there some test points on the board I can check for the compressor and wouldn't that tell me if its the board, or something else?


Does anyone happen to have the service manuaul? 


Thanks in advance.

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It looks like neither the fresh food nor the freezer sections are at the correct temps. The only thing, besides the control, that they share in common is the condenser fan motor and the condenser coil housing. Make sure the coils are clean and that the fan motor is running full speed.

Edited by Spannerwrench

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Good point, the fan was running but maybe not at the correct RPM's?


The condensor was not very dirty, and I was so hell bent on addressing other options I didn't bother cleaning it.


The fact that the compressor relay and overload tested good and the Ohms on the compressor studs tested 'normal' and I didn't have voltage at the wire's leading to the compressor made me think it was a board issue or thermister? 

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Voltage out of control board???..( Looks like Terminal E6 )..............gray wire going to the compressor........What is the voltage, terminal to a good ground/frame....................Close the refer  fan switch, does the evaporator fan motor operate?????........Both are wired to the same terminal on the control board, gray wire...........Clean the condenser coils........

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For this model and series if there is no code shown with the "EC" and "Service" flashing then the "EC" display indicates excessive compressor run time for that particular section.  You can check thermistor temperature readings by initiating the diagnostic mode as follows:


1)  Unit must be on.


2)  Press Colder and Unit On/Off key simultaneously then release both keys. 


After performing the above key strokes, the following will appear on the LCD.  Temperatures shown are for reference only, actual temperatures may vary.


-05          SERVICE (Illuminated)          F

(Temperature of freezer compartment)


40           SERVICE (Illuminated)          r

(Temperature of refrigerator compartment)


-12          SERVICE (Illuminated)          FE

(Temperature of freezer evaporator)


29           SERVICE (Illuminated)          rE

(Temperature of refrigerator evaporator)


Pressing the Colder key at this time will take the display back to the first reading, freezer compartment temperature.


Note:  If "EE" is displayed in place of temperature, the thermistor in that location is faulty.


Diagnostic mode will end 10 seconds after last key stroke.

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