It is not an AIR compressor, it is just "the" compressor.
Lenox does not make compressors. The original might have been a copeland, a bristol, or a tecumseh. As long as the specs are matched up, any good compressor will be a good replacement. Depending on the tons...a replacement compressor will cost the installer between $400 and $800. About 20% more if it is a scroll rather than a recip. And if you buy the Lennox OEM compressor, add a couple hundred.
Depending on the failure mode, replacement could be easy, or if you had a burnout or something, a complete flush, evacuation, and replacement of several pounds of R22 at $10 to $30 per pound , may be needed. I would guess the job would run a couple of hours to 3 or 4 hours.