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Amana NED7200TW Dryer no heat, problem with cycling thermostat?


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37 replies to this topic

#1 triggerhappy007

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Posted 16 March 2012 - 12:10 AM

Hi,
My dryer tumbles but the heater doesn't work. I've checked all 3 thermostats, thermistor, and heater and they are all withing range. The only reading that was out of range was the Cycling Thermostat, it should be 10 K Ω but I'm only getting 6.46 K Ω. Is that the problem with the dryer not heating? How do I fix this? Thank you for your help.

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#2 kdog

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Posted 16 March 2012 - 12:18 AM

Doubtful it is the thermostat as that resistance reading will vary with temperature (10 KOhms @ 25 deg C).
Scan a nice pretty picture of the wiring diagram on that techsheet. Did you try resetting house breaker and verifying proper 120/240v at receptacle ?
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#3 triggerhappy007

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Posted 16 March 2012 - 12:38 AM

Doubtful it is the thermostat as that resistance reading will vary with temperature (10 KOhms @ 25 deg C).
Scan a nice pretty picture of the wiring diagram on that techsheet. Did you try resetting house breaker and verifying proper 120/240v at receptacle ?

Yes, I did reset the breaker and checked the voltages. Here's the wiring diagram:
Posted Image

#4 kdog

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Posted 16 March 2012 - 12:40 AM

Can you measure voltage across black/blue of the heater relay while machine runs on a heating cycle ?

Nicely scanned !

Also measure each of the black/blue to a good ground
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#5 triggerhappy007

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Posted 16 March 2012 - 12:47 AM

Nicely scanned !

Can you believe that's from my phone in a dimly lit room using flash?

I will try your suggestions tomorrow. Thanks for your prompt replies, I wasn't expecting someone to reply so soon. Good night.

#6 RegUS_PatOff

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Posted 16 March 2012 - 01:02 AM

... Here's the wiring diagram:

Posted Image
.

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#7 john63

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Posted 16 March 2012 - 09:16 AM

A SAMSUNG-built dryer.

The temperature THERMISTOR should show 10,000 ohms at 77F

If not---replace it.

In nearly all cases where the THERMISTOR has failed---the *coating* on it has become damaged and the tiny copper winding has a green color (corrosion). This is especially common in areas near a salt-water environment (beach/shore).

See image: http://www.repaircli...ned7200tw-==c61

Also inspect the TERMINAL BLOCK (where plug is attached to dryer) for loose/burnt connection(s).

Edited by john63, 16 March 2012 - 09:24 AM.

To eliminate:

Musty odor

L-O-N-G cycle times

Dingy/yellowing whites

Suds error message

Slow spin speeds

Intermittent water leaks (from rear of washer)

And other annoying symptoms which vary brand-to brand.

Read below:

The *correct* amount of HE (High Efficiency) detergent that should be used in any front load or agitatorless top load washer with tub sizes 3.0 cu ft and larger is as follows:

HE: (2) Tablespoons Per Wash Load

HE 2X: (1) Tablespoon

HE 3X: (1) Teaspoon

Perform a TUB CLEAN CYCLE every (4) months.

Use: "Tide Washing Machine Cleaner"

#8 triggerhappy007

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Posted 16 March 2012 - 09:53 AM

I saw this on another post:

set Dryer to run a no heat Air-Fluff Cycle
On the Controller Board Heater Relay (lower left corner)
Measure voltage from the Black wire to chassis (ground)
and then from the Blue wire to chassis (ground)
should be
120v on each of the wires when running in a no heat Cycle
Then run a Timed Dry heat Cycle.
Then measure the voltage across the Black to Blue wires.
There should be
0v when running in a normal heat Cycle.

On my dryer:
Black wire to ground has 124 V. (normal)
Blue wire to ground has 0V. (abnormal, what does this mean since it's wrong?)
Black to blue has 0V. (normal)


John,
I don't see any loose or burnt connections. The thermistor has the correct resistance at room temp. I put it over my stove and the resistance decreases to about 4,000. I already purchased a new thermistor since when I checked my original thermistor for continuity, it failed. The new thermistor failed continuity also. Shouldn't the thermistor have continuity?

#9 RegUS_PatOff

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Posted 16 March 2012 - 10:03 AM

... Blue wire to ground has 0V. (abnormal, what does this mean since it's wrong?)
... Shouldn't the thermistor have continuity?

1) it means the Heater circuit is "open" (not continuous)
2) no, continuity means 0 OHMs (or nearly)
doesn't apply to Thermistors

edited # 1

Edited by RegUS_PatOff, 16 March 2012 - 10:55 AM.

.

one of my video productions: “Easter Seals: Walk With Me”

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RegUS_PatOff > www.youtube.com/watch?v=oPAY2LsKVEw

#10 triggerhappy007

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Posted 16 March 2012 - 10:35 AM

I see on the wiring diagram that the Blue wire is connected to thermostats 2 and 3 and the heater (those are fine), then the centrifugal s/w. Do you think it's the s/w or the control board?

#11 RegUS_PatOff

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Posted 16 March 2012 - 10:51 AM

sorry, I wasn't thinking straight...
edited previous messages

Something in the Heater circuit isn't complete ...
While still running in the no-heat cycle
test for 120v AC to chassis (ground) at each point in the Heater Circuit
including and up, to both sides of the Motor Centrifugal Switch,
but also up to the L2 connection at the Power Terminal Strip
Find where it does read 120v AC
.

one of my video productions: “Easter Seals: Walk With Me”

every day is Down Syndrome Awareness Day
"A Child Is Waiting" . Burt Lancaster . Judy Garland . 1962

RegUS_PatOff > www.youtube.com/watch?v=oPAY2LsKVEw

#12 kdog

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Posted 16 March 2012 - 09:59 PM

the control board?


If you check that same blue wire to ground with the heat cycle on, you will see the 120v there verifying closed control relay
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#13 john63

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Posted 16 March 2012 - 10:20 PM

<<< I've checked all 3 thermostats>>>

************

On the Heater Housing---there's a THERMOSTAT (larger of the two) and a THERMAL LIMITER (smaller).

Does the THERMAL LIMITER show *continuity* ?

If not---replace it and thoroughly examine the EXHAUST VENT SYSTEM from the rear of the dryer to the outside vent hood (for obstruction/blockage).

http://www.repaircli...ber=NED7200TW10


If the THERMAL LIMITER is "good"...

Unplug dryer

Remove the blue and black wires from the HEATER RELAY.

Push/connect both wires together and wrap with electrical tape.

Plug dryer

Test a cycle and verify if Heater "comes on".

If the Heater functions---replace the MAIN BOARD.

http://www.repaircli...ber=NED7200TW10


If *still* no heat...

The only remaining component in the heater circuit would be the CENTRIFUGAL SWITCH (part of the Motor).

http://www.repaircli...ber=NED7200TW10

Edited by john63, 16 March 2012 - 11:06 PM.

To eliminate:

Musty odor

L-O-N-G cycle times

Dingy/yellowing whites

Suds error message

Slow spin speeds

Intermittent water leaks (from rear of washer)

And other annoying symptoms which vary brand-to brand.

Read below:

The *correct* amount of HE (High Efficiency) detergent that should be used in any front load or agitatorless top load washer with tub sizes 3.0 cu ft and larger is as follows:

HE: (2) Tablespoons Per Wash Load

HE 2X: (1) Tablespoon

HE 3X: (1) Teaspoon

Perform a TUB CLEAN CYCLE every (4) months.

Use: "Tide Washing Machine Cleaner"

#14 triggerhappy007

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Posted 17 March 2012 - 02:03 PM

Yes, the thermal limiter shows continuity.

Plugged black and blue wires from the relay together, turned on, but still no heat.

I tested the centrifugal switch for continuity when the power was off, and leads 3,4, and 5 are continuous. Leads 1, 2, and 6 are not continuous. I also tried to short leads 1 and 2 together and turned the dryer on, but there's still no heat.

#15 john63

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Posted 17 March 2012 - 02:32 PM

<<<I've checked all 3 thermostats, thermistor, and heater and they are all withing range.>>>

************

Has the HEATING ELEMENT been tested for *continuity* rather than *ohms/resistance* ?

Re-test the HEATING ELEMENT---if "open"---replace it...

http://www.repaircli...ber=NED7200TW10


On the Blower Housing---there's a THERMISTOR (10,000 ohms at 77F) and next to it---is a *self-resetting* THERMAL LIMITER. This should show *continuity* as well.

************

<<< I also tried to short leads 1 and 2 together and turned the dryer on, but there's still no heat.>>>

************

A difficult thing to do.

The *only* method for successfully by-passing this switch (wires no. 1 & 2) is to use a JUMPER WIRE of some sort. The connection must be tight/secure for this "test" to be reliable.

A simpler test would be to use the test meter leads---placed on the CENTRIFUGAL SWITCH #1 and #2 connections (not the wire harness)---while an assistant slides the *black ring* on the motor shaft---in the direction of/towards the Blower Wheel. With the Switch closed---your test meter should indicate *continuity* if it's "good".

Edited by john63, 17 March 2012 - 03:29 PM.

To eliminate:

Musty odor

L-O-N-G cycle times

Dingy/yellowing whites

Suds error message

Slow spin speeds

Intermittent water leaks (from rear of washer)

And other annoying symptoms which vary brand-to brand.

Read below:

The *correct* amount of HE (High Efficiency) detergent that should be used in any front load or agitatorless top load washer with tub sizes 3.0 cu ft and larger is as follows:

HE: (2) Tablespoons Per Wash Load

HE 2X: (1) Tablespoon

HE 3X: (1) Teaspoon

Perform a TUB CLEAN CYCLE every (4) months.

Use: "Tide Washing Machine Cleaner"

#16 triggerhappy007

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Posted 17 March 2012 - 02:35 PM

Posted Image

#17 RegUS_PatOff

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Posted 17 March 2012 - 02:48 PM

Something in the Heater circuit isn't complete ...
While still running in the no-heat cycle
test for 120v AC to chassis (ground) at each point in the Heater Circuit
including and up, to both sides of the Motor Centrifugal Switch,
but also up to the L2 connection at the Power Terminal Strip
Find where it does read 120v AC

Motor centrifugal Switch 1 & 2
.

one of my video productions: “Easter Seals: Walk With Me”

every day is Down Syndrome Awareness Day
"A Child Is Waiting" . Burt Lancaster . Judy Garland . 1962

RegUS_PatOff > www.youtube.com/watch?v=oPAY2LsKVEw

#18 sh2sh2

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Posted 17 March 2012 - 03:36 PM

and we are absoulutly sure there is 240 volts from black to red at the terminal block?

#19 triggerhappy007

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Posted 17 March 2012 - 03:41 PM

The heater is continuous.

There's 120V to L2, then pin 2 of the centrifugal switch. From then on, everything else is 0V. When I short the pin 1 and 2 of the centrifugal switch together and test voltage on the heater, it's showing 120V, but it doesn't seem to get hot.

#20 triggerhappy007

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Posted 17 March 2012 - 03:45 PM

and we are absoulutly sure there is 240 volts from black to red at the terminal block?

It's not, it's 0. Each black or red to ground is 120V.






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