Author Topic: Maytag MDE-5500AYW Sensor Dry Nervous Breakdown  (Read 3572 times)

Offline ATLBrysco

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Maytag MDE-5500AYW Sensor Dry Nervous Breakdown
« on: July 10, 2014, 06:04:51 PM »
'ello, all -

Decided to bring this to the experts, because between this dryer and myself, one of us is going to die by the end of the month if this doesn't get figured out. Besides... everyone likes a puzzle, right?

SO - have a Maytag Neptune MDE-5500AYW dryer that I bought new as part of a pair way back before the turn of the century. Both worked flawlessly, until I lost the washer to a tragic incident of the motor speed control board burning out. The dryer still continued to work beautifully until this past holiday, at which point suddenly the sensor dry decided to go wonky on it.

Let me say first, that timed dry works just fine - no issues whatsoever. Based on this, I have a tendency to believe that the thermal fuses, cycling thermostat and hi-limit thermostat are okay. Also, the internal workings of the dryer as well as the ducting throughout are completely spotless so airflow restriction is not an issue.

When sensor dry is selected, the dryer starts up and within two to three minutes, it immediately reverts from 49 minutes to 1 minute for a cool-down, and then shuts off. Now of course, in the service manual, there is that big, ominous warning that says:

"IF THERE ARE NO IMPEDANCE OR SENSOR READINGS WITHIN THE FIRST THREE MINUTES THE DRY CYCLE WILL BE TERMINATED IMMEDIATELY." (9-5)

The dryness sensor circuit of this dryer is made up of the thermistor, the sensor bars, the control board and associated wiring. Here is where the fun begins... NO diagnostic codes are being recorded and the "System Check" activation within the Service mode of the dryness sensor circuit reports normal operations ("Normal" light is lit). To verify the diagnostics, I disconnected one wire from the thermistor and got a diagnostic code of 02 and when taped together, got diagnostic code of 01 for a short. Just to make sure and to eliminate all the parts from the equation the thermistor, sensor bars *and* the control board are all brand new (okay, the control board is refurbished, but "brand new" as to factory standard). Regardless, the problem exists just as it did before the parts were replaced.

I am completely out of ideas on this... it is driving me crazy and I refuse to be beaten by such a simple sensor circuit. Am I missing something here? Anyone have any other ideas I might try?

Barring anything else.. anyone want to buy what has rapidly become Satan in a metal box?

Thanks for your help!
« Last Edit: July 10, 2014, 06:07:03 PM by ATLBrysco »

Offline keithvibe

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Re: Maytag MDE-5500AYW Sensor Dry Nervous Breakdown
« Reply #1 on: July 10, 2014, 06:22:01 PM »
unplug the dryer, remove the wires from the sensor bars. Connect your meter to the sensor bars. Set it for ohm's. Take note of the reading then place your hand on the sensors. Do you see the reading on the meter change?

Offline Wilson13

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Re: Maytag MDE-5500AYW Sensor Dry Nervous Breakdown
« Reply #2 on: July 10, 2014, 10:48:29 PM »
if you have replaced the three parts of the sensor dry circuit all that is left is the wiring from the board to the sensor and thermistor, I'm assuming your running it with wet clothes and its going to 1 min. then shutting off. also check to to make sure you have a good chassis ground from the board.
« Last Edit: July 10, 2014, 10:50:17 PM by Wilson13 »

Offline ATLBrysco

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Re: Maytag MDE-5500AYW Sensor Dry Nervous Breakdown
« Reply #3 on: July 11, 2014, 11:26:38 AM »
unplug the dryer, remove the wires from the sensor bars. Connect your meter to the sensor bars. Set it for ohm's. Take note of the reading then place your hand on the sensors. Do you see the reading on the meter change?

Hi Keith - thanks for the quick reply. To your suggestions, I removed the bar assembly (easier from the inside without taking off the front again) and disconnected it. The results: First measurement (without hand) is infinite ohms (set to 2M ohms); with hand, it registered about 283K ohms.

if you have replaced the three parts of the sensor dry circuit all that is left is the wiring from the board to the sensor and thermistor, I'm assuming your running it with wet clothes and its going to 1 min. then shutting off. also check to to make sure you have a good chassis ground from the board.

Hi Wilson - yes, the quick cycling is occurring with a load of wet clothes so the short is occurring across the bars. I haven't measured the wiring of the unit (dreaded thought), but when I get home I will. Strategy will be to measure end-to-end of PK18a and PK18b (thermistor), BU19a and BU19B (sensor bars). Once I verify no breaks there, I'll measure from J4 Pin 6 to the ground screw for the actual chassis ground line. I'll let you know as soon as I have results.

Thanks guys!


Offline ATLBrysco

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Re: Maytag MDE-5500AYW Sensor Dry Nervous Breakdown
« Reply #4 on: July 12, 2014, 10:19:00 AM »
if you have replaced the three parts of the sensor dry circuit all that is left is the wiring from the board to the sensor and thermistor, I'm assuming your running it with wet clothes and its going to 1 min. then shutting off. also check to to make sure you have a good chassis ground from the board.

Hey Wilson - here is the update - measured resistance on all wiring (as described before) and no opens at all on any of them... in fact, not even partial opens - all are measuring 00 ohms.

Grrr... this is stressing me. >:(

Offline niobrara

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Re: Maytag MDE-5500AYW Sensor Dry Nervous Breakdown
« Reply #5 on: July 12, 2014, 04:25:41 PM »
Try rubbing your bars with some light sandpaper. Shine them up, then throw a couple of damp towels in. Make sure there is enough in that the bars are being touched.

Offline fairbank56

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Re: Maytag MDE-5500AYW Sensor Dry Nervous Breakdown
« Reply #6 on: July 13, 2014, 05:51:03 PM »

  Check the dryer's ground connection. Usually, one of the sensor bars is connected to ground, even if via the control board.

Eric

 

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