29 y/o Kenmore 110 is blowing heater cut-off kits...

[r_benner]

It wasn't heating so I watched youtube vids to learn testing procedures. Here's the exact order I executed:

when I initially began measuring items in the heating chain, I began with the operating thermostat then went to the hi limit thermostat and they both checked out. Then, I tested the cut-off fuse deal mounted up top and it failed. Bought the OEM kit, installed it and got heat.  Well... the heat stopped and I checked the cut-off fuse up top again and it failed... So now I get to buy that kit again but I know something is blowing that circuit so I checked the heating element and it checked out. I also checked the thermal fuse and it checked out. I then checked the operating thermostat heater (purple wires) and it failed even though the op thermostat checked portion out. Do you think I should order a second cut-off kit and the operating thermostat of test further? Thanks in advance for any advice.

Best,

r_benner 

[certified tech group 51]

did I miss the complete model number somehow??/....check your venting...........O.E.M. parts used???

[r_benner]

Sorry #110.96281800 Installed OEM #279816 kit. Venting clear.

[AccApp]

Check the drum seals and the blower wheel. The thermal cut-out cuts out when it gets too hot, usually due to poor airflow through the heater tube. If the seals are bad the blower will draw air from elsewhere.

[r_benner]

 

13 minutes ago, AccApp said:

Check the drum seals and the blower wheel. The thermal cut-out cuts out when it gets too hot, usually due to poor airflow through the heater tube. If the seals are bad the blower will draw air from elsewhere.

Okay, I can do that tomorrow. Might you have a link to that process please? Thanks for your time.

[AccApp]

Search for "whirlpool dryer drum seal" on you tube. It'll take you longer to watch them all then to take it apart and get a look at the seals. I find the rear one tends to get cooked on the electric dryers.

[johntech]

Make sure the connectors are tight on the part that keeps blowing. If the connector is loose it will generate heat and cause it to fail. Check if the heater is grounded. If it is then it will heat till it shuts down. Start it on air dry no heat cycle and see if it heats.

[Budget Appliance Repair]

Also, your cycling t-stat is OK.  The small connectors in the middle of the t-stat that the purple wires connect to will no show a reading if your meter is set at the continuity setting, (the bais-heater in t-stat is usually around 7000 Ohms)

[Mrs. Samurai]

Hey everyone,

r_benner happens to be an old friend of mine, and is an all-around very good guy - thanks for helping him out!

[tech7]

Dryer fabric sheets sucking up against intake blocking air flow?

[MoTeD]

6 hours ago, tech7 said:

Dryer fabric sheets sucking up against intake blocking air flow?

Piggy backing on this. Dryer lint sheet residue can build up on lint screens and cause airflow issues also. To check this, run the lint screen under the tap and see if water flows freely through the screen.

[r_benner]

9 hours ago, Budget Appliance Repair said:

Also, your cycling t-stat is OK.  The small connectors in the middle of the t-stat that the purple wires connect to will no show a reading if your meter is set at the continuity setting, (the bais-heater in t-stat is usually around 7000 Ohms)

As mentioned in my orig post, I did not measure the cycling t-stat until after I bought and installed the cut-off kit... When I measure for continuity, it shows .OL.  My deal is,  I have another cut-off kit and cycling t-stat in my shopping cart but before I spend the $ again can I be sure the bad cycling t-stat was the culprit all along? Not sure I can get my FAT head 'round this as written: will no show a reading if your meter is set at the continuity setting, (the bais-heater in t-stat is usually around 7000 Ohms)

[r_benner]

3 minutes ago, MoTeD said:

Piggy backing on this. Dryer lint sheet residue can build up on lint screens and cause airflow issues also. To check this, run the lint screen under the tap and see if water flows freely through the screen.

I've washed it only one time in it's 29 yr life. maybe a year ago. We keep it fairly clean by hand-picking it each load but I think I'd better include this when I follow ACC APP's suggestion to check the blower wheel and drum seal. Thanks! 

[r_benner]

11 hours ago, johntech said:

Make sure the connectors are tight on the part that keeps blowing. If the connector is loose it will generate heat and cause it to fail. Check if the heater is grounded. If it is then it will heat till it shuts down. Start it on air dry no heat cycle and see if it heats.

Connectors are very tight. Tough to get on and off tight when I measure. In it's current state, I'm assuming it will not heat starting on air dry because the cut-off kit is blown. I have another kit as well as the newly discovered bad (I think?) cycling t-stat. I strongly think the cycling t-stat was the source of the cut-off kit blowing all along but I've only tested those middle connectors for continuity, got none and assumed it is bad. 

[MoTeD]

Should have an ohms resistance reading but not continuity. The larger outside terminals should have continuity. Test the heating element to ground. Make sure you test both terminals on the element to ground seperately. 

[MoTeD]

Also look at the timer. Stuck contacts will make the heater stay on. When was the last time you had the exhaust vent cleaned from the dryer to the outside of the house

[r_benner]

1 hour ago, MoTeD said:

Also look at the timer. Stuck contacts will make the heater stay on. When was the last time you had the exhaust vent cleaned from the dryer to the outside of the house

It's top and btm (larger conns) with one side disconnected, test 0.2ohms. The smaller ones L-R with one side disconnected, test ".OL".  Exhaust vent is clear. Heater element tests 9.8 ohms with both disconnected and positive for continuity. 

[r_benner]

1 hour ago, MoTeD said:

Also look at the timer. 

I can inspect the timer along with the blower wheel and drum seal (if needed) tomorrow. 

[johntech]

You can test for continuity to ground at the heater like moted stated. If no continuity then replace the tco and start the dryer on a no heat cycle to confirm that the heater is not turning on. If it is then I would start testing the timer.  You said the ducts are clear, how have you confirmed this? I would try with the duct disconnected to rule them out completely. The dryer has to have good air flow or it will trip the tco. Air flow can be restricted by clogged ducts or mechanical failures. If the idler pulley, motor or drum rollers do not spin freely they can slow the rotation down enough to cause over heating condition. Same with the drum seals. When you replaced the tco what part number did you replace both parts? One part is the thermal cut out (tco) the other part is the cycling thermostat that directly controls the temperature. If I was still having problems I would measure the out going air temp at the back of the dryer. Have had several of this style dryer build up lint balls below the lint screen. To access you would need to remove the back panel and locate the metal rectangle duct on the left side. There will be a few 1/4” hex head screws to remove and 2 Phillips head screws on top of the machine under the lint screen. Pull the rectangle duct and inspect for clog. 

[vee8power]

Your dryer calls for a 279769 hi limit kit; it has a higher temp fuse.

 

Part number: AP3094224

[AccApp]

The old tco will have a temperature stamped into it’s mounting plate. What did it say?

Edited November 9, 2017 by AccApp

[r_benner]

On 11/8/2017 at 7:05 AM, Budget Appliance Repair said:

Also, your cycling t-stat is OK.  The small connectors in the middle of the t-stat that the purple wires connect to will no show a reading if your meter is set at the continuity setting, (the bais-heater in t-stat is usually around 7000 Ohms)

Okay,

Back into it and think I've FINALLY ruled out the Cycling t-stat's bias heater. when I set my MM to 20k , it reads 7000.

 

"Your dryer calls for a 279769 hi limit kit; it has a higher temp fuse.

Part number: AP3094224"

"The old tco will have a temperature stamped into it’s mounting plate. What did it say?"

 

The orig and newly replaced tcos were both T-stat=250 and Fuse=309

I have to work this in between my regular job sessions and really appreciate you guys. My plan today is to disassemble enough to inspect into blower wheel and drum seal. I'll try to find and follow the air flow path, looking for clogged screens while in there. I hope I find something obvious but if I don't, I'll look into the timer. I just don't want to keep throwing $ at tcos if I don't find what's causing them to blow... 

 

 

[r_benner]

Rear felt drum seal is ok but here is a shot of each side of the front seal:

Here are shots of the intake and lint chute (at blower) seals:

I've not yet tested the timer but found these magnetic parts inside the drum housing. Hoping they are not parts to the timer. Doesn't seem to be a way for them to fall down from the timer knob location. Especially being magnetic...

Is the condition of these seals bad enough to cause the tcos to blow? There was plenty of debris in the lint chute but air did have a path. All clean now.

[r_benner]

wait... that last shot is an earbud...

[r_benner]

Test where the red wires terminate on the timer for continuity. Timer of = open. Timer on = closed. Also tested reds on each side of the motor. Open until I pushed the ring to the motor, then closed.

The local parts guy that sold me the first tco kit agreed that it should've been the one with the 360 degree fuse rather that the 309 he sold me. He was cool enough to give me a slightly used kit with that rating no chg. I guess the only thing to do to move on is to order the foam lint screen and blower seals. Unless you guys thing the felt seal is shot. It's just the two connecting sides that look questionable but the sucker is $26.00. 

 

When I get it all back together, I'll test for the grounding heater in air dry mode as two of you've suggested.

If I'm missing anything, please let me know.