Dehydrator does heat - Kitchen Appliances - Others

They aren't supposed to get hot. A dehydrator blows ambient cool air across the food to dry it. Heat would cause food borne pathogens to grow causing food poisoning. Wow, this one does. As a Food Safety Trainer, I find this very worrying!

https://www.amazon.com/Nesco-American-Harvest-FD-1018P-Dehydrator/dp/B001795P4O

This one will be close enough. you need to test the heating element, thermostat and wiring on it.

https://www.manualslib.com/manual/502061/Nesco-American-Harvest-Fd-1000.html

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What is the make and model please, some dehydrators only have fans and no heating element.
Here is a link to the manual which has a phone number to call if you still have problems:
http://www.nesco.com/customer_support/owners_manual_download/english/
http://www.nesco.com/products/Dehydrators/

There are way too many variables to answer that question. You should refer to the owner's manual for your dehydrator. Some of the variables are the air temperature, humidity where you live, does your unit have a adjustable thermostat, does your unit have heating coils, how thick are you slicing the apples.

Look for the thermal cutoff

Freeze-dried food is quickly frozen and placed in a strong vacuum. This process uses low heat and causes less harm to the tissue, taste and smell of the food. To dehydrate food, heat is applied and moisture is removed through the process of evaporation. This is a low cost method in comparison to freeze-drying.

I had the exact same problem!!! Found the instruction manual under NEVCO food dehydrator.

http://tv.manualsonline.com/mdownloads/942de8cb-c4b8-42d4-a5dd-c29f369b7d7a.pdf

There is a recall on some of these. Check it out here:
http://www.cpsc.gov/cpscpub/prerel/prhtml11/11104.html

It has to do with something overheating. Maybe your unit is covered...

I would think that any dehydrator information would work for you.
You just have to be sure the components are working (ie. fan and heating coil.) A dehydrator is pretty basic.
http://www.food-dehydrator.com/food-dehydrator/books.aspx here is a link for books on a site that sells the product.
You can find a lot of books at the library too.
This might also help, dont let the name fool you: http://www.astray.com/recipes/?show=Dehydrator%20general%20instructions
With some searching on line you will be able to find a lot of instructions and probably even ones for your specific dehydrator.
Look on forms about drying foods and ask for the basic instructions if you find you really need them after looking at the links above.
There might be someone willing to scan them and email them to you.

Take apart the bottom unit that contains the heating element. Hopefully it's put together with phillips screws. Mine are not. I'd have to drill out the brads that are holding it together. Once it's apart, use an Ohmmeter to check the heating element. Be sure to disconnect the fan from the heating element when ohmming out the element. If the element is open electrically, replace it. Good luck in finding a place to purchase a new element.