You've sent a print job to your printer and the green light is blinking, but the printer is not printing. The light blinks for a very long time.
The blinking light indicates that the printer is recieving your print request and will print shortly. If the document you are attempting to print is very large or contains many graphics or images, the printer must spool this data into its memory before printing. This can take quite a bit longer than usual. PDF files are notorious for taking longer than other document types.
In this case, it is best to wait a period of time before taking action. Give the printer 10 minutes and see if it prints.
If it does not print within this window of time, do the following.
1. In the bottom right corner of your screen, you will see a small printer icon. Double click on this icon to open the printer job menu.
2. You will see your print job located there, with other information, including its status.
3. Select the job by right clicking on it and select Cancel
4. The job should cancel itself.
5. Unplug the printer, removing all power and leave it sit for a couple of minutes.
6. Plug the printer back in and allow it to go through its start up phase until the "Ready" indicator light is solid. This indicates that the printer is ready to recieve jobs.
7. You may now attempt to print again.
HP Printer Support