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Thread: Dryer not heating

  1. #1

    Dryer not heating

    Model Number: DV48H7400EW/A2
    Brand: Samsung
    Age: 1-5 years

    Hello
    Dryer stopped heating.
    Already checked to make sure no blockage to airflow.
    Getting good voltage in. Getting voltage out.
    Not good with technical names.
    Checked and got voltage in to circuit board. Turned on and got voltage out.
    No error codes that I could see.
    Did continuity check on following.
    Heater coil good beeping
    Hi limit good beeping
    Lo limit? (Not sure if its called that) no continuity.
    All done with wires off the parts.
    Anything else I should check for?
    Thanks in advance.

  2. #2
    The part I am trying to determine if its bad is called the thermal cut off. Its part of the heat assembly box.
    Trying to get this fixed as quick as possible.
    Thanks,

  3. #3
    The part I am trying to determine if its bad is called the thermal cut off. Its part of the heat assembly box.
    Trying to get this fixed as quick as possible.
    Thanks,

  4. #4
    Doc
    Join Date
    Mar 2016
    Posts
    709
    Both thermostats on the heater should be 0 ohms.
    Sounds like one of them is blown.

    One is the hi-limit and the other is the thermal cut off.
    I would replace both of them, see below.

    I would also unplug the unit and both wires from the heating coil.
    Check the heating coil resistance, should be in the 8 to 12 ohm range.
    Then check from each side or the heater to it's case.
    Both should be infinite ohms.
    If not then the heater is grounded (shorted) and should be replaced.

    What can happen is when a heater grounds out it can run on high and not controlled.
    The hi-limit then regulates the temperature.
    But it's contacts are not very good so eventually it fails (usually they weld together).
    This then blows the thermal cutoff.

  5. #5

    Kenmore Elite HE5 not heating

    Hi Fixers, My Kenmore Elite is not heating. I've got not error codes showing. I've checked the heater coil - have continuity; thermostat - continuity; hi-limit - continuity; thermistor - 13 ohms at 65 degrees; went through the Tech Sheet diagnostics - all checked out; no lint, clear air flow. What am I missing?

    Thanks,

    Osa

  6. #6
    Hi - Fixers. Please please help me!!! I am new to the forum and I hope if I am posting to the wrong place someone will let me know so I can get my post to the right eyes and my dryer fixed. I am posting to this thread as I have similar heating issues and questions about testing dryer components. I have been learning about using a multimeter because my Kenmore Elite HE5, has no heat and no error codes. I seem to have tested everything so many times that Im probably still missing something. With the above mentioned Ohm readings in mind I tested the parts on the heater box - thermal cut off and Hi-limit thermostat and heating element for continuity and resistance. There is continuity on all parts. I got 3.5 ohms on the two thermostats with my meter set to 200 ohms and 13.5 at the heater. The laundry is in a cold room so does that affect the resistance readings? I thought if a part has continuity it is good. Can a part have continuity and still be bad? Someone pleeeeeze help me!

  7. #7
    Doc
    Join Date
    Mar 2016
    Posts
    709
    Have you checked the power.
    The un it must get the 240 volts for the heater to work.

    Try flipping the breaker off/on slowly a couple times. Sometimes you can loose half the line without actually tripping the breaker.
    Check the voltage at the wall receptacle
    L1 to L2 should be 240 volts
    L1 to Neutral and L2 to Neutral, both should be 120 volts.
    If OK
    Unplug the unit and check the wires at the terminal strip in the machine to make sure none are loose or burned out
    If OK
    Check the power at the terminal strip.
    Do this with the heater off and on.
    Be careful as 240 volts is lethal !!!

    I do not have a wiring diagram for this unit but your thermistor resistance seems low to me.
    Are you sure you are reading the scale correctly?

    The rooms temperature should not effect the thermostat resistances.
    It will effect the thermistor because that is what a thermistor does (change resistance with temperature).

    The 3.5 ohms also seems high but this is probably just a zero offset in the meter.

    Since you have the tech sheet (wiring diagram) you should be able to check the full heater circuit (heater, thermostats and wiring).

    If the power is god and the heater circuit is good then all that is left is the control board or the centrifugal switch on the motor.
    I am assuming that this unit has a centrifugal switch.

  8. #8
    Thank you for your reply Denman! Yes, I've cycled the breaker, I've checked the power - 240 at receptacle, 240 at terminal strip. I'm new to multimeters but have watched the PartsDr. Videos several times. I have a Commercial Electric, Cat III MS8301A Digital Multimeter. Click image for larger version. 

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ID:	512 I have the meter set to read ohms at the lowest (200) ohms setting - it also is the continuity beeper setting. It beeps. So, I guess I'm ready to check the control board - do I need to wear a wrist strap thingy (dont have one, could make one) or is there another way to avoid any static charge to the electronics?

  9. #9
    Doc
    Join Date
    Mar 2016
    Posts
    709
    Just ground yourself out before starting.
    If your water pipes are metal that should do it.

    Also note that most modern electronics are not that sensitive to static charges.

    To check for the zero in a metre short the two leads together in the scale you are using so you can see if there is an offset.

  10. #10
    Thanks denman! I am still trying!

    Electronics control board has proper resistance at the control board P4-3 and P4-6.

    So now, I have gone through the entire Tech sheet for "Dryer running but no heat": Line voltage 240, terminal block voltage120,120,240, heating system elements have continuity and control board has proper resistance for heater.

    I'm completely stumped. I really don't want to give up. Anything else I can look for?

    ps:Should the thermistor be 50k Ohms or so? The tech sheet says 14-16k at my room temp.

  11. #11
    Doc
    Join Date
    Mar 2016
    Posts
    709
    I do not have the tech sheet so cannot really help any more.

    I would say that the given thermistor resistance in the tech sheet should be correct .

    I would check that the heater wires at the motor's centrifugal switch are properly connected.
    They are usually red and a heavier guage wire than the other wires going to the switch.

    The only other thing you could do is some live testing.
    But I would need a copy of the tech sheet to help you.
    Also I do not recommend this un;less you are confident in you skills working with electricity.
    240 volts KILLS!!!



    I

  12. #12

    Dryer Testing

    Quote Originally Posted by denman View Post
    I do not have the tech sheet so cannot really help any more.

    I would say that the given thermistor resistance in the tech sheet should be correct .

    I would check that the heater wires at the motor's centrifugal switch are properly connected.
    They are usually red and a heavier guage wire than the other wires going to the switch.

    The only other thing you could do is some live testing.
    But I would need a copy of the tech sheet to help you.
    Also I do not recommend this un;less you are confident in you skills working with electricity.
    240 volts KILLS!!!



    I
    Yes, 240 is seriously serious. Thanks for your help! I did a live test of voltage at the heating element to ground and got 123 from each leg. I will check the wires you suggested - not as a Live test, of course...

  13. #13
    Per the above information about thermostats, "Both thermostats on the heater should be 0 ohms." Can someone clarify these readings on mine: Both thermostats have continuity. Both thermostats are reading 3.5 Ohms. I read here that both should be 0 Ohms. Does this indicate that the problem is with the thermostats even though they have continuity?

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