Sorry you have not yet had a substantive answer. Some days there are more questions than volunteers.
I presume what you are doing is using this service:
https://docs.google.com/viewer
and that you are pasting in the url of your pdf and then copying the embedded viewer iframe tag into your webpage. This works for me.
I tried pasting the url for your pdf:
(a) https://greenwichneighborsunited.com/wp-content/uploads/2014/11/LettertoGovernorKasichconcerningtheOPSB.pdf
into the address bar, and the link was redirected to:
<b) https://greenwichneighborsunited.com/?s=/wp-content/uploads/2014/11/LettertoGovernorKasichconcerningtheOPSB.pdf
This service checks for redirects:
https://www.internetofficer.com/seo-tool/redirect-check/
It confirms that link (a) is getting a 301 permanent redirect to (b).
I copied the html you see in the iframe box into a page. Its not the pdf in html format, its the html for your site’s search results page.
Because the pdf link is being redirected, the Google viewer can’t find it.
So the way forward is to stop your pdf link from being redirected. Redirects are handled by a file called .htaccess in your wordpress root folder. As a test, disable this by renaming it. See if the viewer iframe works or not.
Other things may no longer work. You can make a new .htaccess by going to Admin page > Settings > Permalinks and click “Save changes”. Unfortunately there may be some desirable features of the disabled .htaccess that no longer work, but see what happens.
If your site goes down, restore the original .htaccess. Its always best to take a backup of files and database before doing stuff like this.