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stubborn1

Dryer timer only advances in timed dry

15 posts in this topic

Hi - I'm trying to figure out if I have a bad timer or is something like a thermostat causing my timer not to advance. Its an Amana gas dryer model number LG8409w2. Heat works in all cycles.

I unplugged and pulled open the control panel to start taking some continuity measurements. In the timed cycle, the contacts for the timer motor have continuity. In any other cycle, its open. What do I start looking at next? Do I need to pull the dryer away from the wall and get at the bottom to measure the thermostats, or is there a way from the control panel.

Thanks for the help.

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I can't find a wiring diagram for that model, yet

unless you have one you could scan & upload (somewhere)

 

Usually, in Auto-Dry, the Timer doesn't advance until one of the Dryer Thermostats reach proper temperature.

That Thermostat could be bad, OR the Dryer isn't actually reaching the desired temperatures,

possibly due to weak Gas Valve Coils (common problem)

If you could measure the temperature of the Dryer Vent air while running in auto dry, with an empty load.

Should cycle somewhere between 135F and 160F

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Here's a copy of the scanned one line diagram that was in the control panel.

 

wiringdiagramdryer001.jpg.html%5D" />

 

I'll also check temperature - we haven't noticed any drop in performance and the air still feels pretty darn warm.

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unless you have one you could scan & upload (somewhere)

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Okay, let me try linking this again.

 

http://001.jpg

 

I pulled off the front cover and took some measurements.  I have continuity on the limit stat that mounts on the "tube" that the burner fires in to.  Then I measured a thermostat with five wires that mounts to the discharge air.  I measured the pink to blue which looks to be the normally closed leg and that checked out fine.  The red/blk to blue measured open which is what it looks like it should be at room temp.  Two of the connections are for a thermostat heater.  I read an open circuit across these two connectors. This doesn't seem right - is this thermostat bad? 

 

 

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Some parts are missing from diagram

Fabric Selector Switch on the Connection Diagram

 

It may be easier if you scan the Connection Diagram side by itself

and then the Schematic side by itself

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  The thermostat heater is a resistor that typically will read several thousand ohms. It is used when low temp is selected but would not have an affect on timer motor operation during auto dry. Check continuity of the red/blk wire between thermostat and timer. If good but your timer never advances during auto dry and heat is good, looks like you have a bad thermostat.

 

Eric

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  Test procedure from service manual:

 

Cycling Thermostat (S.P.D.T.)

(1) Set meter to read OHMS.

(2) Apply meter probes to terminals 1 and 3.

Meter should read “zero”.

(3) Remove screws holding thermostat to

exhaust fan cover.

(4) Heat thermostat with a small flame until a

distinct “click” is heard, then immediately

apply meter probes to terminals 1 and 2.

Meter should read “zero”.

 

THERMOSTAT HEATER

c. Disconnect wires from thermostat/heater,

d. Set meter to read OHMS. Apply meter probes

to the thermostat heater terminals. Meter

should read as follows: (Cold Ohms)

120 Volt 60 Hz. 2400 ± 240 Ohms.

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Red/blk has continuity between the stat and the timer. The thermostat checks out okay per the procedure above. Could it still be a stat issue?

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  Possibly. If wiring from thermostat to timer is good but timer never advances in auto-dry, either the thermostat is faulty or it's just not cycling due to dryer not getting hot enough.

 

Eric

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I would swap out the gas coils and make sure the exhaust duct is clean, kink free and not getting squished when it is pushed in against the wall, Then see what happens.These coils deteriorate gradually over tim, convention tells us that timer advance issues in auto dry usually go to the venting. Go for the low hanging fruit first, then get back to us if it still isn't behaving properly.

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Figured I would return and close the loop on this one. I replaced the thermostat and all is well. Thanks for the help.

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Figured I would return and close the loop on this one. I replaced the thermostat and all is well. Thanks for the help.

Good one, thanks for getting back to us, we love to hear success stories.  Doc

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I know you got it fixed but I'll throw one more piece of information out there for someone else reading this. If the element is cycling on the high limit themrostat the timer will not advance on the auto-dry cycle. This is common if the vent is restricted and the high limit thermostat is cycling the element off before the cycling thermostat reaches temperature.

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  That's true on this particular model but that is not a standard as it depends on the model.

 

Eric

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