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Joined: 1/10/2011(UTC)
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One, how do I check the defrost heater? I know where it is but need info on what readings I should get if good or bad, etc.
Two, would that really cause this problem? Seems to me if the coil is completely defrosted to start with, things ought to cool down properly until the frost builds up to where the heater would kick on?
Also, should the fan in the back of the freezer (above the coil) be running constantly, or off and on? Mine seems to run at different speeds, sometimes off. When I fired the fridge up yesterday after letting the coil defrost itself, I only felt a little air moving through the vent at the top of the fridge compartment. Seems like if everything was working hard to cool down there would be more airflow?
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Rank: Member
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Joined: 1/10/2011(UTC)
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Pulled the defrost heater out to check. I have continuity, so that means it's good, right?
I cut the wires to the defrost thermostat and wire nutted them together, then plugged the fridge back in. The thermostat is closed (i.e., I have continuity) at roughly room temperature. I stuck it in our other freezer and will check again after it gets cold.
Also, confirmed that the evaporator fan IS running.
UPDATE: It would appear the defrost thermostat has continuity both when frozen and at room temperature. This indicates that it's bad, correct? Could this be causing my problem? If so, how?
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Rank: Advanced Member
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Joined: 9/10/2007(UTC)
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When the compressor is running, unplug fridg, remove the motherboard cover and locate the 3 pin power connector. Pull the plug out and put a wire jumper between the mating pc board pins labeled line and def.
Plug in fridg, the defrost heater should turn red, if not you have either a bad defrost heater or thermostat. This is a special thermostat the clicks open at over 100 degrees.
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Rank: Member
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Joined: 1/10/2011(UTC)
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With the jumper in place, the defrost heater kicked on and was glowing red within about 15 seconds.
Keep in mind, though, that at this point I still have the defrost limiter thermostat (part #AP3884317) removed and its two wires nutted together. Should I put it back in and run the same test, or run the test with those two wires disconnected?
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Rank: Advanced Member
Groups: Senior Expert
Joined: 9/10/2007(UTC)
Posts: 9,586
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Put the thermostat back in and when the freezer is cold, do the test again.
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Rank: Member
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Joined: 1/10/2011(UTC)
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OK, I put the thermostat back in and let the freezer get good and cold. Then did the jumper test again. Same result, defrost heater came on and glowed red.
What does this tell us? What are we bypassing with that jumper, the defrost thermostat?
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Rank: Advanced Member
Groups: Senior Expert
Joined: 9/10/2007(UTC)
Posts: 9,586
Was thanked: 2 time(s) in 2 post(s)
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It still points to a bad motherboard even if it new. I got a bad new motherboard once and the factory binding was removed when I got it showing it was a returned item.
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Rank: Member
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What do you mean by factory binding? And how do I go about returning this one and getting a replacement?
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Rank: Member
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Joined: 1/10/2011(UTC)
Posts: 32
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I assume by "factory binding" you mean the tape sealing the motherboard box? The one I got was sealed, looked fine. But still, I realize these electronics parts are sometimes defective straight from the factory. That would certainly explain what's going on. I can't figure out what else it would be. Seems like we've ruled out most all other possibilities?
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Rank: Member
Groups: Registered
Joined: 1/10/2011(UTC)
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I've arranged for a replacement. Very easy process. Thanks much, richappy! I'll update when I get the new board.
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