Why does my humidifier holmes 1700 blows air but no water or mist?

Page 2 of the manual has it is words.

https://manualzz.com/doc/52322507/holmes-hm7808-cool-mist-humidifier-owner-manual

https://www.google.com/search?q=change+filter+on+Holmes+HM7808

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, this cool mist tower is ideal for medium rooms. It provides a refreshingly cool, invisible mist, as well as a digital humidistat which offers precise humidity control for your optimal comfort.

I got this off the Sears website so either the room you're trying to make humid is too large, or the humidistat needs to be set properly. Also make sure there is plenty of water in the tank.

attached link for user manual hope this helps
Holmes Owner Guide Cool Mist Humidifier HM7204 ManualsOnline com

I ordered 2 replacement caps from here they were the cheapest tat I found http://www.jardenstore.com/productdetails.aspx?BrandId=494&pid=1783 but they seem to be out of stock at the moment These http://www.appliancefactoryparts.com/humidifiers/holmes/holmes-water-tanks.html are 3 dollars more here hope this helps

This page has 18 pdf user manuals they are only 1-2 pages each open them in adobe reader till you find the one you need wish i could be more help
http://www.holmesproducts.com/Manuals.aspx

I am assuming a lime buildup from evaporated water. Use vinegar or drip coffee maker cleaner.

I have a Holmes cool-mist One-Touch Humidifier, and you can't reach the blades to clean them, and you can't take the console apart. I finally decided to use two spray bottles and clean and them rinse the Humidifer while holding the console upside down and over a sink. The one bottle you could fill with any mild cleaner plus a lot of water to dilute the cleaner. Maybe dishwashing liquid (not the dishwasher stuff), or a little bit of ammonia, or rubbing alcohol, or vinegar. Spray that on the blades while the machine is upside down, and a lot of sooty dirt drips out. Then rinse with another spray bottle full of plain water. Leave the console upside down on a towel to drip-dry. This is also how you can clean silk flowers that collect dust.

unfortunately on a cool mist unit the mist shouldn't show up. on most units that's what it does. the warm mist units show the mist.. the best way to tell is if you put your hand over the spout that the mist is suppose to come out of for about 2 minutes and you pull it away and it feel clammy then it's working. if your hand is still dry please let me know and i'll see what else i can do for you.

possibly calcium or other deposits from the type of water you are using in the unit..........