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Maytag DE408 Dryer - Melted Wiring

Dryer Wiring Overheating

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7 replies to this topic

#1 how2do

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Posted 02 August 2014 - 04:18 PM

- Dryer stopped heating with motor running, then shortly thereafter the  motor stopped but continued to hum

- Opened up unit and found Black wire between heating element and motor input was melted at motor plug--also found other (Purple) wire leaving heating element to cycling thermostat was severely heat damaged at plug on the heater terminal. Both damaged wire ends showed green oxidation on the copper wires, suggesting protracted time for the damage to occur. (I previously replaced these wires with large (10Ga vice OEM 14Ga) wires, and Hi-Temp connectors, for the same reason, about 5 years ago.)

- Checked continuity across Hi/Low/Limiting thermostats at room temp--all good. Also checked them for shut-off at higher temperatures (in an oven), all working properly

- Replaced melted wiring and connectors. Plugged the unit back into the wall and immediately detected heater element becoming hot, even though it had not been turned on at the control panel. Immediately disconnected the dryer from the wall plug

- Checked for ground between heating element and ground and neutral--both tested good (Open)

- Checked for continuity between motor plug (that had the previously melted, Black wire leading into it from the heater) and found continuity from the heater input plug and one of the 120V leads on the wall plug. (the Black wire was disconnected for the test)  I think this should be an Open when the motor is not running

- Does this indicate I have a bad motor switch and need to replace the motor?

Thank you for any insight you might have.



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#2 Samurai Appliance Repair Man

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Posted 02 August 2014 - 07:27 PM

This is caused by a loose connection.  Loose electrical connections have a high resistance and so get hot.  

 

The terminals are close to the heating element/gas burner.  This thermal heat causes the metal in the terminals to weaken and loosen their grip on the component spade they are attached to.  As time goes on, the connection gets loose enough that causes heat, enough heat that the wire insulation burns.  Sensational to look at but really rather unremarkable once you understand the physics.  

 

Repair and re-terminate the connection and all shall be well with your world.  



#3 how2do

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Posted 02 August 2014 - 09:15 PM

Thank you for the reply--I assumed the same diagnosis and repaired the wiring, as stated in the first half of the original post.  Please see the rest of the post after I plugged it back in.  Grasshopper is really confused--the heater is heating as soon as the wall plug is plugged in, without turning on the motor at the control panel!  See details and further testing in the initial post.  In thinking about it further, even if the continuity between the input terminal on the motor (from the heater) to the L2 conductor of the wall-plug is explained by a bad motor switch, I cannot explain why the heater runs when I can't find a synch on the other side of the heater--there is an Open between the heater coil towards the control panel--no continunity to the L1 terminal or chassis ground.  Grasshopper needs wise Master to explain confusing universe (even communing with the dryer has not yielded this deep secret)!



#4 Samurai Appliance Repair Man

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Posted 02 August 2014 - 09:29 PM

Heating element is grounded. Replace it. Part number: AP4290655

Part number: AP4290655


#5 electro_doc

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Posted 02 August 2014 - 09:57 PM

If the heating element is not grounded to the dryer frame ( checked with wires off element and using meter ohm out each terminal of the heating element separately to the chassis of the dryer) should be open.  If this is open then it can only be a motor switch. You can take the wires off the heater terminals and plug the dryer in and check each terminal to a ground, separately and see which line the power is coming from to isolate the problem.

 

Doc



#6 how2do

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Posted 03 August 2014 - 12:13 AM

Re: Heating element is grounded.  With the wires disconnected from the heating unit, I repeatedly checked for continuity between each heater terminal and the chassis (which, by the way is not grounded to anything anyway)--both came up as OPEN.  I reconnected the path between the heater and the control switch (leaving the path between the heater and motor OPEN).  A continuity check of path between each of the heater elements and each of wall plug prongs is also OPEN.  Going the other way, when pull the heater plug off of the motor connector and test from the motor connector and the L2 conductor on the wall plug, there is continuity. Since the wiring diagram shows what appears to be a centrifugal switch in the motor, it appears that this circuit should be OPEN when the motor is off--but it is not, it is going through.  This would suggest a bad (permanently closed) motor switch.  HOWEVER, even with a closed path to the heater through the motor, the circuit is not complete because my testing shows that the path from this point forward is CLOSED to ground and to the neutral (or even the L1 conductor on the wall plug).  Yet, as soon as I plug it in to the wall (I don't turn it on), the heating element heats right up, but the motor does not run--the heater should not be heating unless there is a way to complete the path through the control switch.  My only guess is that when power is applied, something like an electromagnetic switch is being closed to complete the path through the control switch and back to the wall plug.  Again, I have repeatedly tested (with no power applied) and do NOT find a short between the heating element ends and the chassis.  It is relevant, the heating element measures about 15 ohms.



#7 electro_doc

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Posted 03 August 2014 - 01:03 AM

The motor swicth gets power for the element separately from the motor.  The motor does not need to be running to give power to the element if the motor switch is stuck shut.  power from the other side to the heater will come from the timer or  if timer is off it may compleet the circuit some other way, I'm not sure but when you plug in the dryer do you get 110 volts from the wire at the heater coming from the motor?  If the switch is shorted out then you will get 110 volts even if the motor isn't running.  You should not get power to the other leg of the heater when it is disconnected from the heater and the dryer is plugged in and the timer is off. If this is the case then yes, changing the motor should solve this problem.Part number: AP5272724

Part number: AP5272724

 

Doc



#8 fairbank56

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Posted 03 August 2014 - 08:07 AM

  Can you post the wiring diagram? Can't seem to find that old one.

 

Eric







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