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triggerhappy007

Amana NED7200TW Dryer no heat, problem with cycling thermostat?

38 posts in this topic

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.

IMG_20120315_235334.jpg

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Need appliance parts? Call 877-803-7957 now!

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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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:

IMG_20120316_002932.jpg

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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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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.

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... Here's the wiring diagram:

pagefromtechsheetw10162.jpg

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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.repairclinic.com/Sensor-Or-Thermistor-Parts?s=t-ned7200tw-%3d%3dc61

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

Edited by john63

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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?

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... 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

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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?

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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

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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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<<< 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

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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.

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<<<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

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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

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

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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.

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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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there must be 240v from Black to Red

Has this Dryer worked OK up till now at this location ?

Have you re-set your House Circuit Breakers ?

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if there is no 240 from black to read but there is 120 from black or red to white then one of the legs is open and 120 is feeding through the dryer to the other leg...unplug the dryer and test the outlet by itself, you wil find one leg has no power. Lesson learned. When you find nothing wrong with the appliance look elsewear for the problem. Time to call in the electrician

Edited by sh2sh2

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there must be 240v from Black to Red

Has this Dryer worked OK up till now at this location ?

Have you re-set your House Circuit Breakers ?

Yes, dryer worked for almost 3 years at this location

I did reset my circuit breaker before taking the dryer apart.

At the outlet, theres 125V from each side, and 250V when both sides are connected.

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but at the terminal block you said there was 0 from black to red? if so there must be a opening in the power cord or the outlet is not making good connection with the power cord?

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I noticed I hooked up the power cord wrong when I first installed it. I mixed the red and black wires up and had the ground from the power cable going to the white. Now I redid the cables so the ground from the dryer is going to the white, red to red, black to black, and ground from the power cord going to the ground on the machine.

It's getting 250V from red to black of the terminal block. Now, the dryer doesn't turn on at all.

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