I want use only black cartridge in HP920c

SOURCE: Remove and check colour cartridge HP 23, HpPSC500 error

Did you trying cleaning the cartridge contacts on your machine?

SOURCE: hp psc 1510 - only want black ink

Hi Manavoc,

I will explain you the cause for it.

It prints in yellow first and then override with black for better quality. This is the reason your color ink gets empty.

http://h10025.www1.hp.com/ewfrf/wc/genericDocument?docname=c00308490&cc=us&dlc=en&lc=en&jumpid=reg_R1002_USEN

Have a great day!

SOURCE: Ink light keeps flashing

reset the printer by turning it off, waiting 10 seconds and turning it back on, also right click on My Computer and select manage..go to services and stop and restart the spooler service

SOURCE: HP Deskjet F4180 colour lights flashing and printer offline

Hi I have exactly the same problem, and can't scan or make copies. I went to HP Online, and tried their advice, which didn't work. http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00867129&lc=en&dlc=en&cc=us&product=3177566&rule=25623〈=enHP's solution made me realise it might be a scanner problem. I made a wild guess and kept the cover above the glass panel open. Turn off your printer, lift the cover up and turn on again. The lights should stop blinking and you should be able to scan/copy/print. I guess the cover prohibits the device to scan properly causing the blinking lights. Hope this helps!

SOURCE: My cyan cartridge shows as empty. My black

No. You need all the cartridges installed with functioning chips for your printer to work. The reason why you need all the colors when all you print is black is because a small amount of color prints when you print black. The manufacturers want to make up their R&D costs on the printers by selling lots of expensive ink.