Level of DifficultyEasy
Time to do repair15 - 30 mins
Age of Appliance1 - 4 years
First I unplugged the dryer from 240V and removed the back cover upper (behind the switch) and lower (exposing the remainder of the parts)
Inside the upper section was a folded wiring diagram of the dryer (don't know if this was courtesy of Whirlpool or another individual, but it was a very nice touch.)
I did a resistance measurement across the heating coil and found out it was fine. I then plugged the dryer back in and carefully took voltage measurements from one phase of power (this was easily accessed where the power comes in to the dryer, just be careful not to touch or short the wires)
I had an assistant turn on the dryer (this makes things go a little faster, as you are behind the dryer otherwise) and checked for 240V across the heater coil.
Once I did not have this, I kept one lead on the left side wire (one of the power phases coming into the dryer) and moved the other lead to the left (as viewed on the wiring diagram) until I no longer had 240V. This identified the faulty component as the Thermostat High-Limit, non resetable.
I ordered the kit with the High Limit NR and High limit Thermostat (as both had to be bad). I also ordered the 150 degree cycling thermostat (although this was not necessary - for <$20 I opted to replace it as well)
Removing wires one at a time, each component is fairly easy to replace.
My only complaint is that with the combo kit, the wire attachment is a little different that the original component and requires you to cut an existing wire and crimp a different terminal to allow all three wires on the High Limit thermostat (250 degrees) to be attached. There is little to show you how exactly the crimp is to be connected (it goes on the smaller of the three wires - DO NOT CUT the jumper provided and USE A GOOD CRIMPER - not the $2 variety, or you'll be getting a new connector!!) The connector provided is designed for some strain relief from one connector to the other, however) An additional jumper with the appropriate connectors already attached would be a nicer design.
Also, make sure you do NOT screw in the smaller cover that covers the power in until you place the entire lower half cover back on the dryer (unless you want to take it off a second time, as I did...) as it uses a common screw to hold both in place.
Overall, fairly easy to do with a minimum of tools, straight blade screwdriver to remove stubborn wire connectors (esp. for HT thermostat 250), ratchet and socket for quick removal and replacement of covers, and a good T&B style crimper ($10-$20 at your local hardware and well worth it even if you only use it a couple of times)
30 minutes and done - the dryer now cranks out the heat and the advanced settings (Auto dry) work great - no more 2-3 times throug to get things dry.
If you have a minimum of mechanical ability and a little bit of electronic troubleshooting skill, you can check and repair this youself and save about an $80-$100 service call.
Thanks to Part Select for the diagram of the dryer layout as well!! (Schematic would be nice if available online, though!)
Shipped the part in about 2 days from order time, as well. Will be back (hopefully not soon, though, as something has to break first!!!)
Be safe and good luck!
(One last note: Make sure your lint trap is clear including the hose - either due to build up or a lazy kid...as this probably caused the failure as heat could not escape...)