Dryer keeps blowing Termal cutoff fuse - stumped

[tkainz]

I have a Whirlpool WED8300SW0 that keeps blowing the Thermal Cutoff fuse and I cannot figure out why.  I'm stumped and looking for suggestions.  Whenever I replace the fuse, I replace the companion high limit thermostat.  I have also replaced the Thermistor.  I've completely cleaned the machine including the blower - dismantling the machine to do so.  There are no obstructions of any kind.  I've also replaced the drum rollers and the band.  I've made sure that the heater element is not contacting any ground and thus shorting out.  Right now the dryer is on top of the washer and venting directly into the room so there's no issues with the exhaust vent being too long, having too many bends or otherwise being restricted.  The heater element measures 10.4 ohms resistance.  ANY suggestions would be appreciated otherwise it'll be a matter of replacing the heater element next and if I still have issues then the control board..... which at $150+, I'd prefer not to do unless absolutely necessary.  Thanks in advance!

[KarefulKactus15]

When I read your article, two things come to mind.

1.) Air Flow
2.) Feedback / Control Circuit

1.) Airflow,   have you actually put your hand at the exhaust to make sure there is good air flow?  You cleaned everything but maybe the blower motor isn't staying on?  A dryer has to really get cooking to blow the thermal fuse with good airflow. 

2.) Feedback / Control, You replaced all the control components except the board, got some bad news for you if its not airflow.... lol.  As far as your element,  the control circuit should regulate it, even if its bad.   

Wish I could help more. If your super bored, I mean really really board.  Listen to your dryer run, you can hear the elements come on and off possibly hear the lower and upper limit clicks also.   I know when my dryer runs,  the timing is pretty consistent between on and off.    If yours isn't, maybe the board isn't commanding off?   I still have a funny feeling about the air flow.

Either way, let us know what you find!

[MetalCap]

Agreed, my first thought was that your vent is clogged.

[tkainz]

I can confirm that vent clogging or restriction is not the issue.  I 've dismantled the dryer and have cleaned every inch of the air flow channel from the heater baffle through the channel going up the back of the machine and into the drum and then from the drum through the lint filter and channel to the blower and from the blower through the exhaust out the back of the machine.  The time before last, when I changed the cutoff fuse, the dryer actually continued to work for about a week until I threw in a load of about 4 jeans and a few t-shirts and changed the dryer setting to "more dry".  Needless to say, I came back to a load of cold, wet clothes.

I find it "interesting" that a few inches away from the thermal cutoff fuse (and connected in line, electrically) is a high limit thermostat and if I understand the two components correctly, the high limit thermostat should be cutting off at about 295 degrees F with the Thermal cutoff acting as a safeguard and cutting out at about 350 degrees.  Why then would the thermal cutoff fuse keep getting blown?  Wouldn't the high limit thermostat kick off first?

Thanks again

[Spork]

POSSIBLY TOTALLY UNRELATED!!!

I have a similar problem with a Whirlpool dishwasher.   A thermal fuse lasts me about a year.  The last time I bought the part, the guys at the parts store called an old fart repairman friend of theirs and I talked to him.  He basically just said "Those things blow them all the time.  They didn't use to have them up until a few years ago, but they were catching on fire, so they added it to the design."

In our case, the thermal fuse usually blows after running a few iterations of a high temperature cycle.  (Sani-rinse on the dishwasher).  It's my guess that this is a kludge design where the thermal fuse isn't well matched with the temperatures it is matched with.

I'll also mention: on the dishwasher, the replacement part comes with about a 6-8 inch tail of new wiring and a splice block to splice it in.  Apparently it is very important to actually replace the wiring as well (instead of just pulling the wires off the spades and replacing the fuse.  I don't know if the same thing is true of the dryer.

[boarder42]

Simple solution. Hang dry your clothes. That's the most mustachian solution here