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  1. #1
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    Jul 2004
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    manitowoc j series

    previous service company disconnected discharge temperature sensor from board. Is it possible for the machine to run for more than three cycles with this disconnected? Tech support said no but I think its been running this way for a while. Thought about putting resistor across two terminals on board where it was disconected from but didn't.

  2. #2
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    Quote Originally Posted by levi View Post
    previous service company disconnected discharge temperature sensor from board. Is it possible for the machine to run for more than three cycles with this disconnected? Tech support said no but I think its been running this way for a while. Thought about putting resistor across two terminals on board where it was disconected from but didn't.
    The machine should not run with the thermistor disconnected , providing that the board you speak of is the old style board. The new board does not use the sensor and eliminates safeties 3 and 4. You said it is running okay or do you have an issue with it?

  3. #3
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    machine has lots of issues apparently we found a loose ground and replaced defective toggle switch. Compressor also has problems starting sometimes. We have a new ptcr on order. We left the discharge thermister disconnected like we found it. I think it is the old board, it only has three lights. Right and left curtain and harvest light.

  4. #4
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    Quote Originally Posted by levi View Post
    machine has lots of issues apparently we found a loose ground and replaced defective toggle switch. Compressor also has problems starting sometimes. We have a new ptcr on order. We left the discharge thermister disconnected like we found it. I think it is the old board, it only has three lights. Right and left curtain and harvest light.
    I would ohm the thermistor before replacing it.It souds like other issues could have caused a safety stop. The new board acually has no place to connect the thermistor to. The machine can run for a couple of drops with it disconnected before going out on safety 3.( low discharge temp)

  5. #5
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    Ahhhh. YOu actually have a new Q/J series board. It has 4 lights on it though. one yellow 2 greens and 1 red. THere is nowhere to plug the thermistor in on the new board so it could run with out it. Also It would need a one wire Ice thickness probe. The OLD J board had 2 lights on it. It should have alot of trouble running with out a thermistor plugged in. The thermistor can be replaced with a 26K ohm resistor.

    Hope this helps

  6. #6
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    There were B Series boards that had THREE lights on them.

  7. #7
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    Quote Originally Posted by jonbailey19808 View Post
    Ahhhh. YOu actually have a new Q/J series board. It has 4 lights on it though. one yellow 2 greens and 1 red. THere is nowhere to plug the thermistor in on the new board so it could run with out it. Also It would need a one wire Ice thickness probe. The OLD J board had 2 lights on it. It should have alot of trouble running with out a thermistor plugged in. The thermistor can be replaced with a 26K ohm resistor.

    Hope this helps
    LOL! It has been a while since I have actually seen a two wire thickness probe ,but good point. Have you personally seen a resistor used to replace a thermistor on the old board? I was told by some other techs that it will still cause safety stops now and then.

  8. #8
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    Quote Originally Posted by pdrake65 View Post
    ...I was told by some other techs that it will still cause safety stops now and then.
    Using a 26K Ohm resistor shouldn't cause trips on safety limits #3 or #4.

    The resistor causes the board to always see a 130ºF-140ºF discharge line temperature. Safety limit #3 is for <85ºF and #4 is for >255ºF.

    I've used the resistor trick numerous times and it's eliminated loads of nuisance calls.

    I keep a 2K resistor handy for Hoshizaki's too.

  9. #9
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    I haven't had a thermistor issue in a while , but that is surely some good info to know. I'll try that next time.Hopefully Levi checks in on his thread for this. Thanx as always.

  10. #10
    Join Date
    Feb 2008
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    96
    I have to think back on the J series. If I remember correctly, they got rid of safeties 3 and 4. Since safeties one and two actually took care of safeties three and four which are extended freeze times and extended harvest times, which are safeties 1 and 2. I may be wrong though.....a resistor kit was available and you need to disconnect the thermistor forever. I personally can't stand the safety limits. Customers reset the unit by turning the breaker off anyway......especially on the CVD (can't verify defrost) units. HPR system gone bad.........works in warm weather though.

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