How to Troubleshoot & Replace Whirlpool AP6008325 / WP3392519 Dryer Thermal Fuse

Our 19 year old Whirlpool dryer quit heating. After checking the thermal fuse, I found the ignitor electrically open. I bought an ignitor at a local store as there was a national holiday the next day and I did not want the dryer inoperative waiting several days for shipping. I can say AppliancePartsPros is MUCH cheaper for the identical Whirlpool genuine part. While changing the ignitor, I noticed there was an excessive amount of lint in the dryer, which was caused by worn drum seals. I ordered drum seals, a new drive belt, the foam seals for the exhaust duct and new nylon drum bearing set. These were delivered promptly, but unfortunately the 2-piece nylon drum bearing set had only 1 piece. I went on line, used the chat function and was promptly taken care of. The new part arrived fairly quickly, was correct and I installed it. The most difficult part of the project was the rear drum seal which must be glued to the drum. I removed the old seal and sanded off the dried glue. I then set the drum up on a work table, blocked from rolling off with 2x4s, so I could rotate it in place. The new seal needs to be stretched to make it around the drum circumference, so I used small wood clamps to hold it in place around the drum. I then pushed back the fabric, applied a small bead of glue to the drum surface, gave it about a minute to air dry, then repositioned the seal. I worked my way around the drum, rotating it on my work table. The seal installed nicely. Pay attention when you position the drum during final assembly so that the rear support rollers are in place and the seal correctly circles the stationary back wall for the drum. You can check the seal for folding bouth outside and inside. 2 people are advised for this step. One last note, the installation of the drive belt is little tricky, so photograph the belt path through the tensioner and motor drive pulley before you remove the old belt. 

Background: Roper Electric Dryer model REX6634RQ0 purchased new in early 2006 by my wife. Dryer use profile is low to moderate as it was used by only one person (working from home) from 2006 to late 2007 then moved and stored in a dry basement until mid 2009. Moved and used by primarily just two people (plus occasional children visits) from mid-2009 thru late 2011 with three moves involved with in that time. Then stored in a dry shipping container until moved again in 2013. The multiple physical moves may have contributed to the issue I later diagnose in a dryer not heavily used in a typical family profile. Dryer door switch stopped working about three months ago but was switch was set in the on position so no issue for wife to turn it off via the timer dial to be safe (and keep a curious cat from entering the moving dryer.) During a recent use the dryer would not shut off via timer, timer did not advance and clothing was in for about an hour to cook! Luckily no fire resulted. Then upon the next use the dryer would not start. The timer dial also exhibited a very faint humming or buzzing sound when engaging any of the four selections. Investigation: Disconnected dryer and removed back panels console upper and back plate and opened up top panel to access dryer door switch. All open panel trouble shooting performed with room closed off to other people, children, and a curious cat along with disconnecting the dryer during troubleshooting. 1.Jumped (connected) the door switch pins and no difference. Dryer would not start. Tested door switch with a multimeter and confirmed it was locked in the door closed (dryer on) position. 2.Removed thermal fuse on exhaust and tested with multi-meter. Showed as blown / broken so 196 degrees was exceeded. Most likely during that last use the temperature was just under the fuse breaking temperature while the dryer was running and intaking cool air but after shut off the temperature spiked over the 196 degrees and broke the fuse. 3.Jumped the thermal fuse connectors and dryer was able to be started and would run. However, timer still exhibited same faint buzzing sound. And now the heater ran on all four timer selections including "No Heat Fluff". Wife confirmed that "No Heat Fluff" was never supposed to heat even to low levels. 4. Researched Appliance Parts Pros forums for similar issues. Found most likely cause would be heater coils grounding out to chassis. This often would be caused by lint build up on the coils grounding out the coils. 5. Pulled the coil out and found that the coil section that connected between the "back" and "front" of the coil panel had shifted down because the ceramic support at that point had worn down within the metal frame. I was able to revise the coil at that point by pulling the coil off the ceramic support and re-positioning it to better tension the ceramic support in its hole in the metal panel. After doing this, tested the dryer and the heater functioned correct on all cycles and the timer no longer had the faint humming or buzzing sound. The faint humming or buzzing sound was apparently the timer being energized by the grounded coil shorting electricity to the timer. The best estimate of root cause for the ceramic support wearing in the metal frame and then shifting within the coil frame, would be from the multiple moves that have had this unit transported hundreds of miles and experiencing transport shaking in excess what a typical unit would experience. I ordered a new thermal fuse and door switch to get the dryer back into full operation. 

I suspected the gas valve coils as I’ve replaced them before but this time it did not solve the problem. Luckily I ordered all five parts that are related to the heating function including the coils, thermal fuse, igniter kit, flame sensor, and finally the cycling thermostat. I figured while I had the dryer completely apart it’s probably a good idea to replace everything at once since one of the other parts may have failed shortly after. With all five new parts installed I gave her a test spin and she literally fired right up! I only had two challenges during the process, first, the dryer drum will not stay in position until you put the front panel back on so I used a bungee cord to keep it in place while I reattached the drive belt. Second, the one screw that holds the igniter bracket in place is in a bit of an awkward place, had to use a very small crescent wrench to get in there. Additional tips: Disconnect from the power outlet and turn off the gas valve behind the dryer, to open the top panel you can use a putty knife on the two front corners to release the clips or just give the top panel a nice tug forward at the rear left and right corner then simply pull the front of the panel up, change all parts while you’re in there, vacuum out all lint and debris, change the vent duct if bent or out of shape. The overall repair was actually pretty easy, I’d say give it a shot as a repair service could run a couple of hundred dollars and new dryers are getting pretty expensive these days. Good luck! 

I realized my load of laundry was still wet after a normal drying cycle. My first action was to turn the dryer on (2010 gas Maytag centennial) and open the front port to look at the ignitor coil. It never turned orange so I knew there must be a problem with the primary circuit. I shut off the dryer, disconnected the power, pulled it away from the wall, shutoff the gas, and removed the back panel. I then disconnected the wires for the thermal fuse and checked its resistance with a multimeter. When it didn't read 0 ohms and instead read "OL" for "open line", I knew I had found at least one issue and I'd start by ordering a replacement for that. I knew there could potentially be other issues, but I wasn't about to start ordering random parts without acknowledging the first issue. In addition to the coil not turning on, my dryer had a problem with the door switch for a long time. Fixing it wasn't a priority because it had failed closed. This made it so the dryer would still turn on (because it always thought the door was closed), but it wouldn't turn off the drum when you opened the door mid-cycle or allow the drum light to turn on. This was a minor annoyance, but now that I was ordering an important component to getting the dryer to heat, I thought it was the ideal time to also replace that piece as well. Once the parts arrived, I installed the new components with no issue. The website clearly identified that the parts were replacements for my existing part numbers and that turned out to be the case as expected. Before putting the back plate back on I plugged the power back in, opened the gas line, and turned the dryer on to a heat cycle. I peered through the view port on the front of the dryer and watched the ignitor coil glow orange and the flame kick on. I also tested the door switch by opening the door with the dryer running and the drum stopped and the light turned on as it should. After seeing that I cancelled the cycle, disconnected the power once again to prevent the possibility of shorting any components, and finished reassembling the dryer and placed it back in its compartment. Then I successfully ran 8 or 9 loads because my laundry had been piling up for the 6 days I had to wait for the parts to arrive. The dryer works like new again! 

When this happens, the first thing I think of is the heating element. To me, that has been the case 100% of the time in my lifetime experience with our family dryers. BUT! It is always possible the culprit is a thermostat. You don't know until you take it apart and do a visual and/or volt/ohm meter test. A bad heating element will tell on itself instantly with a visual check when you see a break in that heavy spring wire as if some one snipped it apart with a pair of dikes / snips. HOWEVER! In this dryer's case, you have to practically take the whole thing apart just to get to the heating element AND there are 4 types of thermostatic devices that could cause the problem: thermal fuse, high cutout thermostat, and the other 2 thermostat devices. I went ahead and ordered all 4 thermostat devices with the heating element so I only have to take this thing apart ONE TIME! And vacuumed the whole thing out from lint build up to include a new exhaust vent hose out the back. The repair is not that bad if you follow the repair video. It's more time consuming than anything. So I advise, take your time and place each piece apart and place neat and in order along with the screws so you can put back together confidently. The repair video was pretty close to our model. Some minor differences, but close enough. Ok, sure enough it was the heating element for us. Once accessed, I could see the break in the wire of the heating element. No need for any thermostatic devices. But that's ok! I replaced them anyway just in case one of them was going bad to cause the element to break. Never know. Soon, I will order another heating element by itself to keep on hand for the next time and won't have a delay in washing/drying in the home. I will say, when I noticed no heat, I made the order to appliance parts pros right away that night so the only waiting was for the parts to come in. Which was 4 days total because of it being on a Friday night and weekend coming. So really it was about 2 1/2 business days. Pretty darn good! Think about this: if you call an appliance contractor or your home warranty you have to wait to get a human being on the phone, then wait to get an appointment for them to come out (another week), pay them for service fee because they rang your doorbell, let them in your house to diagnose the one part bad, wait another week for their part to come in, then wait for them to call to make an appointment for them to come out if you catch their call during business hours, then wait another week for them to come out to repair. And when technician comes out, deal with their attitude after you ask them to take their shoes off while in YOUR home. And if a home warranty, get calls from them to tell you what they are NOT going to do for you. And lastly, pay any other fees they want to include they make sure you pay your monthly fees for having the warranty. The only other way that may work for you if your not good at repairs, is if you have a local company that serves your area with a good reputation of taking care of you and they sometimes have those parts on their truck. That's ok, you will pay more for that. Appliance parts pros has been awesome for us because I have a pretty good idea of what's going on and can figure things out. I order my parts, they come to the door step, and I get to work. You want to talk about money saved and peace of mind not having to deal with knuckleheads coming into your home not knowing who or what attitude your gonna get!!! I am a BIG fan of Appliance Parts Pros! Thank you! Mr. Meyer. 

After turning off the breaker and then unplugging it, I opened the rear panel and reviewed the wiring diagram on the back of the control panel. (thank you Daddy for showing this girl how to read a circuit diagram!) Ohmed all parts along the heating system circuit and all were 0 ohms as they should be, except the heating coil which was infinity. Removed the coil and found it had snapped at one point near the middle. Performed a temporary fix by clearing the charred section of the coil and twisting the two ends together, tightening and cleaning until I got 10.6 ohms across the terminals for the coil. (should be 11.08 ohms per the specs) That got it working in the short term. (enough to at least dry the load that was already wet) Came here since I had such a great experience when my washing machine died a few years ago and the videos and comments here made diagnosing that issue a breeze! Found my model dryer and looked up other people's experiences with this dryer. With their comments in mind, I not only ordered a new heating coil, (plus a spare against future failure) but a new Cycling Thermostat, Thermal Cut-Off Kit, and Thermal Fuse... which accounts for the parts that are nearly 80% of failures of the heating system of this dryer model. Once the parts arrived, (super fast shipping... they were here in two days!) I spent an hour replacing all the parts with my new ones and vacuuming out the interior. I saved the old parts (except the temp-fixed coil) for future use should any of the new parts fail, since they were known good working parts when I took them out. 

* Replaced the old dryer thermal fuse with a new one - initially I thought the original fuse had no continuity, but I later verified that it actually did (i.e., user error on my part with the multi-meter). * Confirmed continuity on both thermostats and the heating element. * Replaced thermal cut-off fuse on the heater due to no continuity. * Heat returned for one dry cycle, but cut off again for the second dry cycle. (It must be a symptom only and not the root cause.) * Instead of replacing the thermal cut-off fuse again, I "reset" it by banging it a few times on a solid floor surface (front patio concrete in my case) as recommended on a couple YouTube videos, which worked like a charm to restore continuity on both the new and old thermal cut-off fuses. * Did more research on YouTube videos and learned that the root cause of chronic overheating and thermal cut-off fuse failure may be a clogged exhaust vent, hose and/or duct. * Diagnostic test by a trained technician confirmed there were no other underlying electronic issues and that cleaning the dryer and duct were probably the best next steps to prevent recurrence of the overheating and thermal cut-off fuse failure. * Wiped and brushed the dryer exhaust pipe and the wall duct pipe of accessible lint / dust / debris. * Replaced the old dryer duct hose with a new one (secured with clamps and proper duct tape). * That's where we're at currently. Hopefully having the dryer and wall duct professionally cleaned will do the final trick. (Landlord hasn't had this cleaning done in years, and I'm actually just now learning that it should be done annually.) 

Symptom: The dryer's control panel would light up; however, the drum would not start. A diagnostic test showed "F4/E4." (Note: This dryer has no history of issues and worked flawlessly for almost a decade prior to this problem.) I researched the problem online. I found that it could be as simple as a faulty Thermal Fuse (WP3392519//AP6008325) or as difficult as several bad components, to include the aforementioned Thermal Fuse, the Thermistor (WP8577274//AP6013514), and/or the Electronic Control Board (WPW10542001//AP6022778). I erred on the side of caution and ordered all three parts. While they were being shipped to my house, I thoroughly cleaned lint, hair, and other debris from the inside of the appliance after I removed the top, back, control panel, lint screen, lint screen housing assembly, lint duct, door housing, and exhaust pipe. I also cleaned all the parts I removed, and I used my backpack leaf blower to blow accumulated lint through the exhaust pipe behind my dryer and out the vent on the side of my home. When the parts were delivered, I removed the old Thermal Fuse and Thermistor and replaced them with the new ones. I had plenty of room to do so via the back of the dryer even though all of the online videos I could find showed the fix being done after removing the dryer drum, which I did not want to do. I reassembled the dryer and tested it. Since it had returned to normal working order, I did not install the Electronic Control Board, which was still in its unopened manufacturer's box.. I opted to return it for a refund. (Note: Do not open the box that contains the Electronic Control Board until you are sure that it is needed to complete the repair.) As a result of this experience, I have learned some very valuable lessons. First, despite having no background with appliance repair, I am very capable of fixing and maintaining the washer and dryer in my home as long as I do the proper online research. Second, I will perform dryer-related lint cleanings about every 18-24 months in the future OR sooner if I notice the that "Clean Lint Screen" light stays red continuously. 

Our Estate dryer at first, up and stopped heating. It didn't make sense because when I started a cycle, everything came on as it should including the igniter and gas. But after it would run for a while, I discovered that the igniter continued to come on but the gas no longer did. Replaced the gas solenoid coils and that solved that issue. When we started our dryer, you could hear a quiet rattle coming from the timer knob, but being a timer I thought this was normal. This has always been this way since we bought our house and the dryer came with it. This relates to the next part of my repair. Two weeks went by since the coil repair, and one day I realized the dryer was set on a low heat 35 minute timed cycle, but was still running after an hour or more. I had started it like normal, it heated up, seemed to run through the entire cycle into cool-down, and then the timer stopped advancing right before it clicked into the off section. No big deal, i'll order a new timer and just use my phone or an egg timer to start and stop it until the new parts come in. When I started it up tho, I waited a minute and realized I didn't hear the normal pops and bangs for when the igniter and gas come on. Using the small view hole in the front of the dryer, I could see that the igniter was not coming on anymore, and I didn't head the gas come on. Since I had just replaced the coils I knew those were good, so I pull the back panel off to start checking again, and found the thermal fuse was not open. I think that the timer has been dying since we got the dryer first off, but when something gave way inside of it this time, it caused the dryer to run indefinitely which burned out the thermal fuse. Since I had to do all this and everything was apart anyways, it's always a good time to take the shopvac to the entire machine. 

The thermal fuse burned out 2 times - this little guy is on the blower duct right where the blower pushes air out of the drum and into the exhaust duct. It cuts power to the Motor but NOT to the Heating Element! First time I cleaned out the inside of the dryer cabinet and vent duct from dryer all the way to louvers through wall (I used a shop vac but you can buy a brush/flexible line kit online that you spin with your drill). Also cleaned out the lint trap duct (mine goes from the top lid of dryer down the back to the blower fan, 4 screws to take it off and it was 50% clogged with 15 years of debris!). Thought that fixed it, dryer worked fine for 4-5 loads, then thermal fuse blew again, normal sized loads, no breaker trips or anything unusual. Further investigation proved my Cycling Thermostat (on the blower duct near the Thermal Fuse) and Hi Limit Thermostat (on the Heating Element where power wires connect) were good - multimeter showed continuity at room temperature, heated 'em on stove and heard em click open, continuity was lost at high temperature - this is how they are supposed to work, turns heater on when closed/has continuity, turns heater off when open/no continuity (Cycling Thermostat keeps it 120-160* or so, allows and cuts power to the Heating Element. The Thermal Fuse is a backup in case the Cycling Thermostat sticks closed/keeps heater on forever - it blows when the blower/exhaust duct air reaches about 196*. The Hi Limit Thermostat is on the Heating element itself and is a failsafe that is supposed to cut power to the heater if the heater reaches about 250*). Multimeter also showed my Thermal Cutout had continuity (this is a fuse above the Heating Element near where the heating duct goes into the drum, it blows at 309* as a backup to the Hi Limit Thermostat, in case the Hi Limit thermostat is stuck closed/keeping heater on forever). I took the Heating Element out, and had to yank it really hard, bending the uppermost heating coil in the process. On closer inspection, I found a tiny 1mm arc electrical burn mark and scratch on the inside of the heating duct and on the coil - they had fused, and me yanking really hard broke it free and scratched the duct. The arc burn mark was about the size of a pen tip and would have been invisible without a bright light. This must have created a short circuit, bypassing the Cycling Thermostat on the blower exhaust duct (opens around 160*) and blowing the Thermal Fuse on the blower exhaust duct (blows around 196*). I assume if we had not noticed the drum not turning, eventually the Heating Element would have gotten above 250* and maybe activated the Hi Limit Thermostat (or maybe bypassing it cuz it was arcing and grounding out) and blown the Thermal Cutoff fuse at 309*? Anyway I believe the root cause was the old Heating Element warping over time, and the coil grounding out against the Heater Element case, causing the heater to stay on by bypassing the Cycling Thermostat. I replaced the Heating Element, and since I had it apart and the parts were cheaper than a technician's service call, I replaced the old Cycling Thermostat, Hi Limit Thermostat, Thermal Fuse, and Thermal Cutoff fuse with brand new ones. Also replaced the drum belt/rollers/tension spring since I had the machine torn apart and the parts were cheap (one roller did not spin freely, and enough resistance might burn out the expensive motor in the future). After replacing parts, I checked current to the motor and heating element with clamp meter, got what I expected, about 5 Amps on the motor with drum+belt removed, about 24 Amps when the heating element was on, 0 Amps when the heating element was turned off by the Cycling Thermostat. Realistically, the project took me 2-4 hours of troubleshooting, hopefully my lengthy description helps someone else save hours of time troubleshooting. Heater, 2 thermostats, and 2 fuses took about 15 minutes to replace. Belt, rollers, and tension pulley another 15 minutes.