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MargretS  
#1 Posted : Wednesday, August 27, 2014 12:47:11 PM(UTC)
MargretS

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Joined: 9/8/2011(UTC)
Posts: 28

Last week I replaced a blown thermal limiter fuse. (The dryer had presumably overheated due to inadequate air flow while trying to dry a too-large quilt.) Now the dryer works okay except for the following three symptoms:

1. Opening the door while the dryer is running doesn't stop it. (The door switch does correctly turn the interior light on and off.)

2. The dryer starts without having to press the start button.
(The dryer starts immediately when the timer knob is rotated into the "on" range.)

3. When the dryer isn't running, I hear an occasional series of clicks. This is presumably the relay that controls the automatic periodic reversing of the drum rotation.
(To be specific, there are 4 clicks, then about 30 seconds later 4 more clicks. Then about 5 minutes later the pattern begins again.)

I don't hear any unusual sounds while it's running. The timer seems to work fine: the dryer stops when the timer knob reaches the end of the cycle. The clothes dry okay. The dryer cools down properly after it stops running.

I searched the Dryer Repair forums but didn't find any threads that appear relevant.

I presume the most likely cause of the problem is a short circuit. I hope someone can help pinpoint where I should look for the short circuit, or suggest other possible causes of the set of symptoms.

Since the problem began after I replaced the thermal fuse (which required removing the front panel and the drum in order to reach the fuse) I would first suspect a short at the heating element, because I might have bumped the heating element with the back of the drum while reinstalling the drum. (It's a bit of a trial-and-error struggle to mount the drum's rear bearing into the bearing holder without being able to see them.) On the other hand, since the clothes dry okay and I don't hear the drum scraping on the heating element while the dryer is running, a short in the heating element seems less likely. But I'm no expert.

I haven't examined the heating element yet because it's a pain to remove and reinstall the drum. It's much less of a pain to look at the circuitry on the inside of the front panel, so I've eyeballed those circuits, but nothing there looks obviously wrong.

Also, is it safe to operate the dryer in this condition?

Thanks in advance for your assistance,
Margret
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denman  
#2 Posted : Thursday, August 28, 2014 2:06:44 AM(UTC)
denman

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Here are your parts
Parts for Frigidaire FSE747GES1 Dryer - AppliancePartsPros.com

Could be that the Start Switch contacts are welded together.
Unplug the unit and both wires at the start switch.
Then measure across the start switch with a meter.
Should be infinite ohms.
Should be o 0 ohms when activated (pushed or turned).

If the switch is OK then odds are that it is the electronic control board.
I am doing a bit of guessing here as I could not find a decent copy of the wiring diagram.

I doubt it is related to your heating element as the element circuit is separate from the motor circuit.

As an aside be sure to lubricate the rrear bearing with high temperature greas when reinstalling it.

It should be safe to run this way.
But as usual there is a but and in this case the but is that it will probably blow the door switch in time.

If you do not own a meter, I would suggest you purchase a one. You can get a decent digital multimeter for under $20.00. You do not need fancy though it is nice if the leads are a couple feet long.
If it saves ordering one unnecessary part it has paid for itself and you end up owning a useful tool.
Most places will not let you return electrical parts so if you order it, you own it.
A couple things to watch when measuring ohms and continuity
1. Always remove power from the machine otherwise you could blow your meter.
2. Always disconnect at least one side of any device you are checking. This eliminates the possibility of measuring an alternate/parallel circuit path.
3. When checking for closed contacts and continuity use the lowest scale (Usually 200 ohms). Then try higher scales. This scale is 0 to 200 ohms so if the device you are measuring is 300 ohms this scale would show an open circuit which it is not, you are just measuring outside the scale's dynamic range.
4. When you start always short the meter leads together. This will tell you that the meter is working and if there is any 0 offset.

There is a good STICKY at the start of this forum about it's use.

I am off to the lake later today so will not be available till next week.
THIS FORUM IS DEAD!!!!!!!
MargretS  
#3 Posted : Thursday, August 28, 2014 3:56:22 PM(UTC)
MargretS

Rank: Member

Groups: Registered
Joined: 9/8/2011(UTC)
Posts: 28

Thanks, denman, for all the tips.

High resolution photos of the Frigidaire FSE747GES1 wiring diagram can be viewed at:
http://www.flickr.com/photos/99587016@N05/
The wiring diagram is divided into 3 photos.
(Other photos of the dryer are there too. All were shot in mid-2013.)

The start switch measures okay: 0 ohms (closed circuit) when the start knob is turned, and infinite ohms (open circuit) otherwise. (My digital multimeter is smart: it has a single setting for the entire range of ohms, so I don't need to think about which range to use.)

You wrote that the heating element is separate from the motor, implying it's unlikely that a short at the heating element is causing the symptoms. But actually a yellow wire connects one end of the heating element to one of the motor's terminals.

Thanks again for your help, and for the help of anyone else who wants to chime in,
Margret
MargretS  
#4 Posted : Sunday, August 31, 2014 2:25:13 PM(UTC)
MargretS

Rank: Member

Groups: Registered
Joined: 9/8/2011(UTC)
Posts: 28

Here's some additional diagnostic information:

The three symptoms disappear if the drum & belt are removed.

The three symptoms returned when I reinstalled the drum & belt.

(When reinstalling the drum & belt, I tried to be very careful not to disturb the heating coil when I mounted the drum's rear bearing onto the bearing holder. This is because I haven't ruled out the possibility that the drum is causing the heating coil to short to ground; perhaps this kind of short could explain the symptoms. Unfortunately, it's not easy to mount the drum while looking at the rear bearing, because the dryer is stacked on a washing machine and the pair are nestled in a corner of the kitchen so that I can see the rear bearing only by climbing onto the kitchen counter surface.)

Can anyone suggest what the problem may be and how to fix it? Hopefully someone can suggest a procedure better than repeatedly reinstalling the drum hoping to get lucky.

Thanks in advance for your help,
Margret
MargretS  
#5 Posted : Thursday, September 4, 2014 12:30:33 PM(UTC)
MargretS

Rank: Member

Groups: Registered
Joined: 9/8/2011(UTC)
Posts: 28

I solved the problem, although a mystery remains.

Two wires had detached from the timer: the black wire from pin R and the tan&tan from pin X. Reattaching them made the symptoms go away.

The detached wires were hard to see from some viewing angles, because there's a jungle of wires at the timer. I noticed them when looking down from above the front panel.

I've learned a lesson about the order of disassembly & reassembly steps: When disassembling, disconnect the two wiring harness connectors before removing the front panel. When reassembling, connect the two wiring harness connectors after installing the front panel. Otherwise, the weight of the front panel can tug on the wires when the front panel is moved, and the wires with the least amount of slack will feel most of the tug and can be pulled off their terminal lugs.

The mystery is why the symptoms also disappeared when I removed the drum & belt. But I don't have time to figure that out, and hopefully there will never be a need to know.
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