(covers information from several alternate timelines)
Andor was an inhabited planet. By the late 24th century, this Federation world was considered to be of comparable strategic importance as Berengaria, Vulcan and even perhaps Earth. (DS9: "In the Cards"). An array of subspace relay stations linked it to Rigel. (TNG: "Conspiracy", okudagram)
In 2293, the location of Andor in the Milky Way Galaxy was labeled in the star chart The Explored Galaxy, which was on display in Captain James T. Kirk's quarters aboard the USS Enterprise-A. (Star Trek VI: The Undiscovered Country, okudagram)
Some time before 2363, as a junior officer, Lisa Cusak was assigned as an attaché to the Federation embassy on Andor. She met an Andorian civilian who worked at the Andorian Agricultural Ministry. The two ended up dating for 6 years. (DS9: "The Sound of Her Voice")
In 2373, Kai Winn rhetorically asked Captain Benjamin Sisko if the Federation would be willing to sacrifice Andor, Vulcan, Berengaria or even Earth to protect Bajor from the Dominion if necessary. (DS9: "In the Cards")
In 2366, in an alternate timeline, during the Federation-Klingon War, the location of Andor was labeled on a tactical situation monitor in the ready room aboard the USS Enterprise-D (TNG: "Yesterday's Enterprise", okudagram)
See also Edit
Background information Edit
"an-DOOR" was the pronunciation for this planet's name from the script pronunciation guide for "In the Cards".
In Star Trek: Enterprise's season 4 DVD, writers Judith and Garfield Reeves-Stevens have said they made the Andorian homeworld a satellite of a gas giant to help explain why both names Andor and Andoria have been used interchangeably. Andor was the gas giant and Andoria was the moon. According to StarTrek.com, Andor was an alternate name for Andoria. 
In Star Trek Maps, and Star Fleet Medical Reference Manual, Andor was referred to as the Andorian homeworld. According to Star Trek: Star Charts (page 52), Andor was the name of the capital city of Andoria.
According to Worlds of Star Trek: Deep Space Nine, Volume 1, the difference between Andor and Andoria was the same as the difference between Terra and Earth. Andoria and Earth being the names preferred by the natives.