Searching the manufacturer's website is usually the best way to find an online manual for a food dehydrator. If you can't find a specific make or model on the manufacturer's site, or if the manual you need is no longer available, you may be able to find it from other online sources.
Major manufacturers such as Nesco/American Harvest and Excalibur typically provide downloadable manuals on their official websites.
On the Nesco website, a sidebar on the main page provides a link to the company's Customer Service page. Once there, click the Owner's Manual Download link, and specify whether you need a manual in English, French or Spanish. This opens a list of links each leading to a user's manual in Adobe PDF format. You must install Adobe's Acrobat Reader or other PDF reader to view the files. If you prefer to receive a printed hard-copy manual, call the customer service department at 800-288-4545, as of 2015. Nesco charges a nominal fee for physical manuals.
From the main page of the Excalibur website, access the owner's manual download page by selecting Support from the top menu and then clicking Product Manuals. Select your model from the available options, and then click to download.