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The dryer is blowing the thermal cut out fuse on the heating element cage.
The first replacement lasted 20 loads the second only 1.
After the last one blew I have removed the lint chute and pulled a couple of handfuls of lint from the blower wheel area with no noticeable increase in air flow. I have also bypassed the thermal fuse and get a reading of ~155 degrees from the exhaust of the dryer. The thermal fuse is open, and so is the heater thermostat (ring around operating thermostat?) but the high limit and operating thermostat have continuity. The heater element has resistance within spec and is not short to the case.
Is there a anyway to test the heater thermostat or operating thermostat.
Any ideas and thank you.
Rich
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The vent is not obstructed. I have tested the operating Thermostat by using a hair dryer. It appears to open at 155 and close at 120. I have also bypassed the operating thermostat and was able to get the high limit thermostat to open so I know that it is functional too. I also pulled the element and it looks good (no breaks, no sag).
Is it possible that the blower is not drawing enough air through the drum and is there a test. The current exhaust feels pretty strong and the three flaps on the outside vent open up. I found a test for the exhaust. I took a 2"x2" piece of paper and placed it in the dryer. I let it run and when I opened the door the paper was on the vent.
Thank you
Rich
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Possible there is more current drawn by the motor than it suppose to be. The thermal fuse is in the motor circuit. You have to have a special clamp on meter to measure it.
Gene.
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I would run the unit in an air only cycle, if it blows the fuse then you know it is a motor problem.
Pulling a handful of lint out of the blower is perhaps a clue.
I would open it up and give it a good cleaning.
Also check that the blower wheel is tight on the motor shaft.
Could be that it is partially stripped so it grabs most of the time but every once in a while it lets go.
Also check the filter screen and the holes at the back of the drum.
Especially if you use liquid fabric softener. It can leave a coating and drastically reduce air flow. |
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Have you pulled the heating element to see if it was hitting the case, and causing the thermal fuse to blow? I did notice, you said you in your initial e-mail that said the resistance to element didn't show that it was ground to the case. I have been fooled before. Just wondering if you pulled it to eye ball it. Tom ApplianceEducator.com
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I don't really want to put another fuse in until I know for sure what is causing the problem. I have pulled the element and it looks good. I also ran the machine with the element housing laying on the ground to see if it shorts when heated and it appeared good. I am thinking about putting a thermometer in where the thermal cutout fuse goes and trying to measure the temperature to see if clearing the lint was the problem. I don't think so since I can't tell any difference in air pressure coming out the vent.
Could it be a timer issue. I have been running a few loads through trying to figure it out and have noticed that the AUTO setting does not move that quickly. The timed mode works fine and I am running a Knits load now.
Thanks for your responses.
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I really like denmans idea. Put another fuse in, and run the dryer with a no heat setting, and see if it blows. If it does it is the motor. Other then the element it is the highest drawing amperage in the unit. Tom ApplianceEducator.com
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Do not have the wiring for this unit but I doubt it is a timer problem.
It is normal for Auto to run slower than Timed Dry.
The timer only advances when the heating element is off in Auto. |
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Denman,
Thanks for that bit of information. So if I understand this right when the dryer is in Timer mode the cycling thermostat or high limit thermostat is controlling the heat. In Auto the timer needs to get feedback from the cycling thermostat to advance? How does the timer get that information?
I am thinking of starting over with my diagnostic testing. Can you validate my logic?
1) Bypass TCO on heating element cage (already open)
2) Bypass Cycling thermostat to test high limit Stat on heating element cage ( I should see the heating element shut down in Auto mode once temp is high enough) If it does move to test cycling thermostat
3) Bypass High limit thermostat to test Cycling thermostat ( I should see the element turn off at a dryer vent temp of 160 degrees
If the all of the above tests good it means I am having problems getting the heat from the heater element to the dryer vent. Do you know what the temp in the drum should be? I figure I can through an instant read thermometer in the drum and get a reading that is close.
Thank you,
Rich
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