Amana LGA60AW Dryer won't ignite

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Old 01-07-15, 08:27 PM
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Amana LGA60AW Dryer won't ignite

While I've had several problems with my dryer in the past few months (after years of good service), my most recent problem has me stumped.

Recently, over the course of months I replaced the blower fan, belt and high limit thermostat (each was very obviously broken). Then the dryer started to take much longer to dry clothes. Initially I thought it might be that the metal shim that came with the HL thermostat needed to be in place to back it further away from the combustion tube, but that didn't seem to help. Then two days ago, I found that the gas would not ignite though the dryer tumbled clothes fine and would time out normally. I thought I might have moved the small gas valve adjustment and tried changing that but it made no difference. With the dryer on, the igniter would glow red, there would be no combustion and then go out. After a short time, it would try again. There appears to be no gas to light.

Reading this forum and others, I found that one of the main causes for this type of failure are the two coils which control the gas. This afternoon I bought the pair (which is the only way they're sold), and installed them, but no luck.

So I removed the flame sensor and checked the continuity which is fine. Reinstalled it, and of course no combustion. I also checked the continuity on the cycling thermostat and the high limit thermostat. Both were fine. I've double checked to make sure the gas valve for the dryer is open, and the small valve is open as well. Some gas dryers have a thermal fuse, but I can't see anything like that on this model. Of course I've checked that there's no lint blocking the vent.

Since the gas control unit seems to be my next guess, but is considerably more expensive, I thought I'd ask if there may be something I'm missing, or if there's any other component I might check.

What else could be wrong?
 
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Old 01-07-15, 08:50 PM
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Welcome to the forums.

If the igniter is working then all the safety stats are ok.
The igniter lights for about a minute.... do you hear a loud click when it shuts off ?
 

Last edited by PJmax; 01-07-15 at 09:06 PM.
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Old 01-07-15, 09:11 PM
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No, there seems to be no click either when the igniter comes on or off. I've never really noticed a click in the dryer though. Usually when I've observed it, the igniter will glow and at a certain point the flame seems to simply erupt. There may have been a click when the burner would shut off, but at this point there's no click at all. I need to add that I was careful to keep the metal sleeve on the coil with the three electrical leads to it (it's a three lead plug), and the other (two lead plug) coil didn't have one.
 

Last edited by bfester; 01-07-15 at 09:26 PM. Reason: further info
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Old 01-07-15, 09:40 PM
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I'm leaning towards the flame sensor. After the igniter glows for 30-60 seconds it should click and allow the gas valves to open.
 
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Old 01-07-15, 09:43 PM
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I checked the continuity on that and it quickly pegged the meter. That's why I assumed it must be good. Other than continuity, is there any other test to check it?
 
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Old 01-08-15, 03:38 AM
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Usually igniter will either not work at all but you said it glows red? Usually will glow white before it starts fire. Been retired a while Pete may be able to verify this. Can count on 2 fingers the amount of gas valves I have seen go bad.
 
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Old 01-08-15, 06:52 AM
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Actually it glows all the way to white. Yes, from what I've read, it's very rare for a gas valve to go bad. Other than continuity, is there another way to check whether the flame sensor is working? It pegged my ohm meter last night when I took it off the dryer and checked it directly. Other than that, I have no way of knowing whether it's sending a signal to the coils to open.
 

Last edited by bfester; 01-08-15 at 07:28 AM.
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Old 01-08-15, 03:14 PM
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The flame sensor shows shorted normally. After it detects the heat of the igniter.... the contacts open.

The flame sensor allows electricity to reach the igniter. The igniter then heats up to a temperature high enough to ignite the gas. Once the igniter is hot enough the flame sensor releases the igniter circuit which allows the current to run through the coils that open the gas valve.

If you look at the diagram below.... you'll see the flame sensor is directly across the main valve solenoid. Once the igniter reaches full heat the flame sensor opens and the gas valve becomes energized.

So either the flame sensor is not releasing or the igniter is not glowing hot enough.

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Old 01-08-15, 05:34 PM
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Would this mean then that when the dryer is off (not tumbling), there would be no current on either post of the flame sensor? Then when the the dryer is turned on, even initially before I can see the igniter start to glow, the should be current on one of the two posts (actually the one connected to the igniter). Then at the point where the igniter starts to glow white, there should be electricity going to the the coil (which would open). if I don't have current in either of those situations (and if the flame sensor is defective, especially the latter), then the coils are not activated to open the valve and release gas to ignite. I'm not sure how much, but I should see something.

I'll go check this now.

Measuring current at the posts on the flame sensor with the dryer off, there's no current at either post. Initially with the dryer tumbling, there's no electricity at either post until the igniter starts at which point both posts seem to register the same amount (I'm seeing 110v AC). The igniter glows to a light yellow, for a few seconds (maybe 5 though I didn't count), and then starts to go out. At the point where the igniter starts to dim of course there's no current at either post.

It would seem to me that if there's electricity coming out of the posts on the flame sensor, the gas valve should open, however I would have thought that there would be electricity only on one post (the one that circuits to the igniter), and that there wouldn't be a reading on the other until after the igniter got pretty well warmed up.
 

Last edited by bfester; 01-08-15 at 06:01 PM.
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Old 01-09-15, 12:35 PM
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Update

Using a electric bbq lighter, I tried to see if I could find some sort of combustion with the dryer tumbling and the igniter white hot. There is no gas at the burner.

So today, I bought a new flame sensor assuming that if the sensor was the problem, then it wouldn't send a signal to the coils to open, so that gas would flow.

Nope.

Given that I've replaced pretty much every related component with the exception of the burner, and the cycling thermostat, I'm thinking it must be the gas valve. Since the cycling thermostat would eliminate the igniter from turning on to begin with (and continuity was fine when I checked it), I'm assuming it's not that. And since the burner is simply a mechanical funnel for the gas to light once the igniter has reached a certain temperature, I can't see how that would be the cause. Does anyone have any better idea what might be wrong?
 
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