Kenmore refrigerator 795.77312600 not cooling

[jhb0761]

I have been working on a Kenmore 795.77312600 refrigerator that does not cool down.  I have replaced the control board  (part# 6871JB1375H) and continues not cooling.  The voltage going to the compressor drops out. ( resistance on compressor, overload, and PTC are all good) The thermistors resistance are ok and respond to temperature changes. The defrost circuit checks out. The damper motor opens and closes. Evaporator fan and condensor fans are ok, The temperature control and display is Ok.  The unit goes into each service mode without any problems and there are no errors displayed. I have followed the LG service manual to no avail.  Anyone have any ideas?

[JWWebster]

Might be in need of gas, what ya think? Is the condenser lines warm? Got frost pattern on the evap?

[tgoods]

The only thing I can think of is maybe a thermistor is losing resistance once it has voltage going through it.  Does the manual show the voltage drop of the thermistor? If it does, check it while it's running to see if it's within spec.

[jhb0761]

Thanks for the quick replies.  I have a full frost pattern on evap coil.  Both refrigerator and freezer thermistors are within specs, condensor coils are warm.  It ran for two hours and died out again, Losing voltage from in between board and PTC, the wires check out ok,  Anybody have a full wiring diagram there is no spec sheet in it.