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#21 |
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![]() These timer motors run constantly I thought?
The switch seems to be in series with the compressor, so they disable it, run a heater cycle to defrost, and then allow power for the compressor again. You could check the timer motor's resistance (pin 1-3) to see if it is open-circuit or not. The leads are not soldered to the tabs so maybe a bad connection. Some diagrams show a resistor or fuse "C"? in series with the timer motor. Sankyo/Hitachi TMDFX05CD1 is a special cycle time, 6min/12hr. TMDF706CD1 is close, 7 minutes defrost with 8hr cycle (50Hz). |
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#22 |
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![]() The schematic of this fridge is in post#11, You can see that the thermostat switches the a/c on and off to everything but the fridge lamp. The defrost timer only runs when the thermostat is closed, When it is time to run the defrost cycle the compressor is turned off. The defrost cycle time is not that critical as the amount of frost built up is also not predictable.
Last edited by R_J; 03-01-2021 at 11:06 AM.. |
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#23 | |
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![]() Quote:
Last edited by SuperAman; 03-02-2021 at 01:56 AM.. |
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#24 |
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![]() I don't know which one it is but if you look at the schematic, there are two, a thermal fuse and a defrost thermo (thermostat) , You said that when you turned the defrost timer so it would defrost that it was working and heating up. if this is the case both thermo devices must be working.
Did you check the defrost timer motor resistance? If the defrost element was heating up when you turned the timer to its defrost position, you have likely found the problem, if the other parts were bad it would not heat up. Last edited by R_J; 03-02-2021 at 11:17 AM.. |
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#25 |
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![]() If the fridge runs say 6 minutes every hour (10% duty cycle) with a 6min/12hr defrost timer (wired to the compressor) it will defrost every 5 days for 1 hour. Seem too long to me, but not relevant to OP's problem. It might be a schematic error.
I've had problems with a leaking door seal on the freezer causing the evaporator coils to ice up. Reposting the schematic for the Hitachi fridge. The fixed thermostat in the evaporator coil goes open-circuit when it's hot, but will read zero ohms cold - Some popular defrost thermostats: Open 45°F, Close 25°F, Differential 20°F; another is Open 55°F, Close 35°F, Differential 20°F. Not zero ohms at room temperature. So the thermostat needs close to freezing or colder for the switch contacts to close. |
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#26 |
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![]() I believe the defrost timer in my fridge works like this, for every 6 hours of "compressor run time" the timer will then defrost for 25min.
The TMDFX05CD1 = for every 12H of run time it defrosts for 6min Last edited by R_J; 03-02-2021 at 06:54 PM.. |
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#27 |
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![]() So can I replace mine with one that runs 6, 8, or 10 hrs? I don't think I can find one locally that runs 12hrs. Importing one would be cost prohibitive (customs duties and all).
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#28 | |
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#29 |
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![]() I don't know what the timer motor resistance will be, but it is likely fairly high, If it reads anything but open it is likely ok. You can replace it with a different duty cycle, it's not that critical, It doesn't know how much frost is built up at any time so anything will work better than nothing, If you put a lot of hot steamy food in the fridge it will frost up faster.
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