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  • Dishwasher error

    Posted by beef on January 8, 2020 at 1:08 pm

    Hobart AM15VL showing wrench and P1 on the display. Changed all probes and error still shows as soon as the unit turns on. 

    fixbear replied 4 years, 2 months ago 6 Members · 17 Replies
  • 17 Replies
  • fixbear

    Member
    January 8, 2020 at 2:24 pm

    I’m not certain, because you have a steam condenser on this machine, but it sounds like the rinse thermistor is either open or shorted.  Being they use a extension harness, it could just be connectors for the probe.  Ohm out the thermistor at both the board and the probe..

  • beef

    Member
    January 8, 2020 at 2:32 pm

    All probes are new and proper resistance.  What I found was the conductor to the wash tank heater contactor coil (when disconnected) has 120v to ground while the unit is off. Turn it on, verified 5vdc to the relay that conductor comes from, has no voltage when connected to coil but has voltage when disconnected. Tells me that the relay contacts are bad. So I’m thinking the P1 is a low temperature code. 

    Appreciate the assistance. 

  • olivero

    Member
    January 8, 2020 at 3:34 pm

    What does the manual say the error code means?

  • fixbear

    Member
    January 8, 2020 at 4:05 pm

    I’m talking about the thermistor in the rinse booster tank. 

  • ectofix

    Member
    January 8, 2020 at 4:32 pm

    This is from a 2004 AM15 manual:

  • olivero

    Member
    January 8, 2020 at 5:35 pm

    Did you replace that probe in the booster tank like mentioned?

  • fixbear

    Member
    January 8, 2020 at 6:37 pm

    My brain must be going on the fritz.  P1 is wash and P2 is rinse.  Thank you for the clarification Ectofix.   But again, Hobart uses an harness and multiple plugs.  Short sensor leads to enable a multitude of machines with one sensor.  Also makes it easyier to replace.Don’t confuse the level probes or PH probes with the thermistor.

  • indianatech

    Member
    January 9, 2020 at 2:48 pm

    P1 is open or shorted wash thermistor. I am not sure but I think that if the resistance gets outside of certain parameters (too cold or hot) it may show up as shorted or open. 

  • beef

    Member
    January 9, 2020 at 4:44 pm

    Can’t get a hold of the manual but I have changed all probes on the unit and the error still shows. What pointed me towards the idea that it is a low temp alarm for the wash is that the wash heater wasn’t getting power due to a bad relay contact that sends 120 to the coil of the heater contactor. I’ve got the new board now, I’m gonna be doing it tomorrow and will update ??

    And to top off the thought, I wouldn’t get 5vdc to the relay that sends the 120 to the contactor coil if it was an open or shorted probe. 

    • fixbear

      Member
      January 9, 2020 at 6:21 pm

      But did you ohm the sensor?  If it is open or the harness cable connections are open, it will not heat.  That’s why we have DVOM’s   Your assuming it’s the board. Without testing the probe you don’t know for sure.  Go back one step to the input.

      I realize your new to the forum,  but I’m not one to pull punches or dance around answers.  And I will call out any tech that just replaces parts..  To be a Tech means that you Know the problem, how to troubleshoot it,  and can back up the answer.  We all do get brain fog at times, but we are here to help solve the problem.  Not guess.

      Have I been wrong at time’s?  Hell yes  We unfortunately don’t get to hear and see the machine. We only get what is told to us by the one asking the question. Often tainted by what they believe is the problem.  We like Facts.  And we all have our own field experiences that we start to thing in a channel.  I’ve done it, and I know.

      • ectofix

        Member
        January 9, 2020 at 6:38 pm

        Please forgive me for being so slow as to allow you to beat me to the post…AGAIN!

        LOL!

    • ectofix

      Member
      January 9, 2020 at 6:31 pm

      <div>I tend to interpret Hobart dish machine’s error codes P1, P2 or P3 as ones due to the board seeing temperatures  that are WAY out of range…instead of a problem with heating of the water.</div><div>

      For instance, on our Hobart flight machines, they will show an error if a probe’s reading is <32° or >212°F.  Obviously those temperature ranges are blatantly abnormal.

      The failed output you’re seeing to the heat relay may be just a consequence of the board’s inability to sense proper temperature.  I’m thinking the board is detecting that probe way out of range will prevent it heating for safety reasons.

      Hobart’s dish machine temp probes are 100kΩ NTC thermistors.  That means their nominal rating is around 100kΩ of resistance at room temperature.  NTC means negative temperature coefficient, so their resistance goes down as the temperature increase.

      If there’s a faulty connection between the board and the probe (as fixbear had suggested), then the board will potentially see a resistance that’s out of range (<32° [an OPEN]or >212°F [a SHORT]) and therefore show the error code you’re seeing.

      Having new probes doesn’t ensure that the probe’s CIRCUIT is good.  That only means that the probes themselves are NEW and PROBABLY good.

      I’m suggesting using the test points in IndianaTech’s picture to take a resistance reading of the probe’s circuit to the control board in order to determine if there’s problem with the two wires (or connections) leading from the probe to the board.

      </div><div>

      </div>

      • ectofix

        Member
        January 9, 2020 at 6:36 pm

        Der’s dem dadgum <div> things again!

        Mr Mayor, tha’s not from copying and pasting.  Just like THIS post, it was all typed in a REPLY box.

        • techtownmayor

          Member
          January 9, 2020 at 9:04 pm

          Sorry! I’ve got a developer working to figure this one out asap. 

  • indianatech

    Member
    January 9, 2020 at 11:34 pm

    I believe ectofix and fixbear are on the right track with this. Just because the probes have correct resistance does not mean that is the resistance reading you are getting at the connections to the board. If I remember correctly those probes have short leads that connect to a harness. If the harness is shorted or open you would still have the P1 code because the reading is outside of parameters at the board. 

    Here is a chart that goes down a little lower on the temperature/resistance of the thermistor. So if you are measuring it at room temperature you will have a little better idea of where you should be. 

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