Speed Queen AES68AWF service question

[paulg]

After 13 years of good use, my beloved Speed Queen seems to have developed an issue. The clothes seem too hot when removed after the dry cycle. Airflow, exhaust and seals are fine.
I have the service manual, but it lacks a schematic and timing cycle. I feel I know what is likely the problem but I want to check with the experts for opinions or perhaps field experience.

One test I did is to start the machine in the cool-down cycle and extended tumble cycle. The heating element comes on and cycles. This may or may not be normal as I don't have the schematic or timing chart.
The service manual refers to a "cycling thermostat" as something to test and a potential cause of this symptom. This would be the thermostat that advances the timer during automatic dry cycles. This appears to be the thermostat on the blower shroud (Correct?)
Service docs appear to go back to the timer repeatedly as to cause. This seems logical. What I may do is replace both the cycling thermostat and timer at the same time. Comments?
ON A RELATED (or unrelated note... I will ask another question.
As any dryer ages, failures can occur with any part. I am tempted to replace the heater box thermal fuse and limit thermostats (high limit) purely due to aging.
So my question to the techs is this: For aging clothes dryers, do you find there is a particular time in the life of a clothes dryer where replacement of the heater box thermal fuse and high-limit is prudent purely due to aging?
Thanks for any insights!

 

[paulg]

A quick recheck...

I referred to the owner's manual once again. They refer to extended-tumble as having no heat. However, dialing directly to extended tumble and turning the dryer on causes the heating element to cycle.
Looks like my timer contacts for the heater have fused closed. Agreed?

 

[DADoES]

 
Cool down on any cycle and the extended tumble option should not involve heat. 
The cycling thermostat doesn't initiate power to the element, it just manages the current sent from the timer.

 

[combo52]

Speed Queen Dryer Running Too Hot

You either have a bad timer or a shorted heating element if it heats on air-tumble, it is easy to take the heater out of this dryer to inspect for shorts.

 

John L.

 

[paulg]

Success!

Here are the parts replaced. More on this story - with a little twist.. soon

 

[paulg]

Info...

John, you were correct with the heater being easy to remove. Great idea to check that.
I did remove the element and it was in good shape. Tight, no sag or shorts.
BTW, the schematic and cycling chart was inside the control housing. Glad to have it.
Essentially, this repair was rather routine, but it did have a small twist... and I have some research to do.
My logic was this... The timer had such a great chance of being faulty and it had seen 13 years of daily use - it was time to change it regardless.
Along with the timer, I elected to replace the thermostat and high-limit on the heater as well as the cycling thermostat for the timer. This was purely for maintenance and maybe unnecessary, but the additional cost didn't bother me. The grille got scorched at some time in the past. I was lazy and elected to replace it rather than clean it.
One major reason I changed all thermostats was caution largely due to a dryer-fire symposium I attended in Benton Harbor some years ago. I am a CFEI (any CFEIs or CFIs out there?) and part of my job for a large TV/Appliance manufacturer was to evaluate fires of electronic and appliance goods and report to legal.
Well, in that dryer-fire symposium they illustrated a case history where a 1950's era dryer ( a department store brand) caught fire because all of the thermostats had fused closed over time.
That case didn't leave my mind and so I replaced all the thermostats.
Fortunately for me, the Speed Queen parts depot is very close to the house. While there I ran into an old-timer (excuse the pun) and asked him to opine on what HE thought a good rule of thumb was to replace thermostats in an aging dryer.
When I worked for electronics company, MANY products had hourly part replacement guidelines which were often not published. For example, a VCR used in commercial service (ex: security) may need its head replaced at 9999 hours, the pinch roller at 8888 hours etc.
Was there any rule for dryers?
This gent looked at me and (knowing his audience) said, "YOU keep your dryer clean, right??"
"Always super clean!" I said, trying not to roll my eyes.
"Well, if you keep your dryer clean of lint and fabric softener deposits, you may not have to change the thermostats at all. My dryer is 25 years old and still has the original thermostats."
All right, this is one person's opinion. Not gospel nor fact but an interesting notion.
At any rate, the dryer operates normally now with parts replaced. I however do NOT know exactly where the fault is. I now have to begin FORENSIC work on my dud parts to determine true cause. There was one additional part I changed (not shown).
More to follow...[this post was last edited: 8/28/2018-09:17]

 

[paulg]

The extended-tumble switch

When I pulled the control panel to replace the timer, I found that the extended-tumble switch had damaged contacts. The switch still operated per ohmmeter.
Off to the parts depot I went. Got another switch and replaced it and the spade lugs.
Two theories here.
We have used extended-tumble continuously for thirteen years. This could be the natural degradation of the switch due to aging.
However, my second theory is related to the heater erroneously cycling on during extended-tumble.
This switch may not be expecting the additional load of the heater during extended-tumble. Therefore this switch may have been stressed as a result of timer failure.
Theories only. Now I have to try to prove...

 

[lorainfurniture]

I would guess your timer was the culprit. You can test the red and green tstat by ohming when cold and then putting heat to it. You can use a heat gun, or just a lighter. It won’t tell you if it’s accurate, it will just tell you if the contacts are welded.

That other fuse is a thermal fuse. Once overheated it pops and no heat at all.

All of those tstats just interrupt the circuit when a temp is reached. During cool down there should be no power there to begin with.

 

[DADoES]

 
IMO replacing parts that are not failed or confirmed deteriorated/erratic can be a crap-shot considering the typical poor quality nowdays, LOL.  An original part could conceivably outlast a replacement.

 

[paulg]

But I used Speed Queen exact replacements!

No cheap substitutes here!
I used the exact original replacements. I am confident in their quality.
I can dry my clothes in CONFIDENCE!!

 

[lorainfurniture]

It may sound weird

But I agree with dadoes. Simply unplugging a spade connector can make it not seat as well as it did the first time. That in turn creates resistance =heat.

 

[paulg]

Good information for all

It is entirely true that removing spade connectors (or virtually any electrical connector) can weaken the grip or induce contact resistance. I am aware of that phenomenon and have encountered it repeatedly over the years.
It is a good tip to note for those readers here who (understandably) put a bit too much faith in spade (or gripping) connectors that appear tight. Especially in high-current appliances, it doesn't take too much resistance at a connector to overheat it or make the circuit as a whole malfunction.
(A good example is repeated failed fuses in the "tight" fuse-holder. You know what I mean...)
But I made a judgement call. I'd rather have new thermostats and trust my judgement on the connectors than leaving the original thermostats in. I'm in the dryer often enough and so I'll keep an eye on it as always.
I learned long ago that the first things to do when evaluating a malfunctioning device is to use your senses. The best piece of test equipment is the brain. Although not always present, I always look for overheated / yellowed anything when opening something that malfunctions. I think it's just good practice.
Thanks for adding this important and overlooked tangent of electrical product service.

I was going to end it here... but one last note.
Although, again it is true that removal/reinstallation of electrical connectors can weaken them, I have MANY times encountered cases where I traced a malfunction to a tight spade. I then removed the tight spade and reinstalled - ELIMINATING the resistance at the lug and restoring operation. So the inverse is also true in my experience.
That being said, many of us on this forum have decades in these industries and that comes from having expert judgement. Do I perform a given procedure ... or not? We veterans of this industry have remained viable because of our well-honed ability to choose a given service procedure very accurately on a case-by-case basis.