At my Whit's End! Samsung DV56H9100EG/A2 keeps blowing the thermal fuse!

[rottenjeff]

Model Number

DV56H9100EG/A2

Brand

Samsung

Age

6-10 years

I have a DV56H9100EG/A2 (6-8 yrs old) that stopped heating. I found that the heating element was bad so I replaced it and all of the sensors (high limit, thermal fuse, thermistor and the motor cut-off fuse). It got nice and hot, but apparently too hot and blew the thermal fuse. I cleaned all the ducts (they were fine), found no short in the heating element, replaced the thermal fuse and put the old high-limit back in. Same thing - heat and then no heat - thermal fuse blown. So using two high-limits, I blew 2 thermal fuses. I bypassed the thermal fuse and ran it and was able to watch the high limit cycle on and off - turning the element on and off. (Is it possible that I have 2 bad high-limits that are both opening too late?) So the control board seemed to be the next option. I replaced it and it blew the thermal once again. Reading through some of the posts I decided to test the wiring. The thermistor on the blower housing is at 11K at both the thermistor itself and the connector. The thermistor on the heating duct in the back is at 310K at both the sensor and the connector. The heating element wires (Red and White) are good to the control board connectors and the heating element blue wire is good to the connector at the motor.

I've got 2 sets of sensors arriving tomorrow, but I'm not too optimistic. The only thing I haven't replaced that might make sense is the heating duct thermistor at the back of the dryer. I'm not sure what its room temp reading should be but mine was at 310K.

This one is really throwing me for a loop. Any ideas?

 

[rottenjeff]

Correction - The heating element wires (Blue and White) are good to the control board connectors and the heating element Red wire is good to the Thermistor. The blue wire from the Thermistor is good to the motor connection. I haven't stripped down the wire harness yet, but does anyone know where the 2 black wires to/from the Thermal Fuse eventually wind up? Does anyone have a wiring schematic for this machine? When my sensors arrive tomorrow I'm going to run a test with the thermal fuse connected but not screwed into the housing, keeping it farther away from the heat. If it blows, then I'll have to start figuring out what is causing (surge, etc.). If it doesn't blow after a few loads, I'll put it back in place and see what happens. If it blows then it'll appear that the thermal fuse is blowing at a temp before the high-limit opens - and then I'll have another problem to look at.

And - just in general - How can the thermal fuse blow without a failed or faulty high-limit thermostat? It's supposed to be the last line of defense against overheating.

Sorry for the long posts - it's just that I've seen a lot of people that are struggling with this and I'm hoping that just maybe we can get to the bottom of it.

 

[Jake]

I couldn't locate the wiring diagram/schematics for this model.

If your air flow is good through the dryer and out the dryer exhaust vent, it should not keep blowing that thermal fuse.

This has been a common problem with no solution unfortunately, but the MEDIUM HEAT setting seems to keep it from continually blowing that thermal fuse, look here:

DV218AEB Samsung Dryer Keeps Blowing Thermal Fuse

Yes, electricity will take the path of least resistance....closed relay contacts, or through diodes and such in a meter.....a closed relay will show nothing as the electricity will go through the relay before the meter, once the relay contacts open and the power has no choice but to go through...

www.applianceblog.com

 

[rottenjeff]

Thanks Jake. I decided to put the high-limit thermostats into the oven. I ramped them up starting at 270 degrees to see when they would open. Finally at 315 degrees for 5 minutes neither of them opened up. So it appears that the high-limit was failing which caused the thermal fuse to blow. When I ran the dryer with a jumped thermal fuse, the high-limits would cycle on and off but it was probably at a temp way higher than its 260 degree rating and higher than the 320 degrees which blows the fuse. Some of my parts were from Amazon, so after reading some of your comments I just ordered all new sensors @ AppliancePartsPros.com.

FWIW - Shouldn't the high-limit thermostat kick in before the thermal fuse blow? So if the thermal fuse blows, something likely must have gone wrong with the high-limit. Maybe that's why people are getting it to work for a while at medium temperature - the high-limit is bad but the medium temperature setting doesn't crank out the 320+ degrees that would blow the thermal fuse.

 

[Jake]

FWIW - Shouldn't the high-limit thermostat kick in before the thermal fuse blow? So if the thermal fuse blows, something likely must have gone wrong with the high-limit.

Yes, that is exactly correct.

But on the one I had in Quartzsite, AZ a few years ago I replaced the high-limit thermostat along with the thermal fuse and it still blew it on HIGH HEAT, but on MEDIUM HEAT it didn't. That what puzzled me. My dryer temps were below 200 degrees F even on HIGH HEAT.

Let us know how it goes when you get the parts.

 

[rottenjeff]

My guess is that faulty high-limits are to blame. And I'm talking about the replacements being faulty. I just got 2 that I ordered the other day from Amazon - before I ordered the OEMs. The first one was a complete dud - no connectivity at all. The 2nd one had connectivity but didn't open until somewhere near 320 degrees. It's a 260 - 50, so that's way too high. I've had several that have done the same thing. My guess is that when the thermal fuses are being replaced, the High-limit Thermostats that are also being replaced haven't been tested for the high-limit. People assume they're good because they have room temp connectivity. Then they fail, the thermal fuse blows and everyone is ticked that the thermal fuses keep blowing. You have to replace the high-limit when you replace the thermal fuse - every time! And you need to test the high-limit for its cutoff temp.

BTW - while I'm waiting for my OEMs to arrive, I hooked the dryer back up but didn't connect the thermal fuse to the housing for testing purposes. It's dangling safely below, away from the heating element. What I wanted to see was if there was some sort of electrical surge situation causing the fuse to blow. So far it's humming right along so it looks like it's blowing because of the high heat - which is what it is supposed to do.

I'll circle back once the OEMs arrive. But you better believe I'll be testing the high-limit's cutoff temp before I use it.

 

[rottenjeff]

And being an engineer I can't settle for "just use the medium heat setting". We've got to figure out what the heck is causing this situation.

 

[Jake]

Yes, I completely understand.

Let us know how it goes when you get the new OEM parts installed.

 

[rottenjeff]

Yes, I completely understand.

Let us know how it goes when you get the new OEM parts installed.

Well - the OEM parts I got are not going to be reinstalled. IO tested the high-limit cutoff temp and it varies between 328 and 330 degrees. With a 320 degree thermal fuse you can see what the problem is going to be. I really think there's just a bad supply of the high-limits which don't cutoff in time and wind up blowing the thermal fuse. These parts came from AppliancePartsPros.com so the are supposed to be OEMs. I read somewhere that a tech on here used whirlpool replacements instead of Samsung, as they performed much better. Is there any way to see what a comparable Whirlpool part would be?

 

[Jake]

Is there any way to see what a comparable Whirlpool part would be?

Only by the temperature number on the Whirlpool high-limit thermostat that compares to the Samsung High-limit thermostat.