FixAutoAC wrote:days before it quit I could hear a metallic crushing noise associated with the a/c been turned on, and would go away when turn off (meanwhile the a/c was still blowing cold).
Yes, that sounds like a bad compressor to me (do not run it further). I'd disconnect the compressor wire if you decide to wait for spring to fix it, compressors typically engage with defroster turn on. My 2004 Frontier compressor seized in September, made bad noise while driving but silent when AC was switched off, the AC clutch bearing and idler pulley were fine. Issue is: with that situation, one has no idea if or how much contamination made its way through the high pressure line or the condenser to the drier. On modern AC systems, those should all be replaced except the high pressure lines can be backflushed with solvent.
FixAutoAC wrote:What do you guys think of using a compressor from a junkyard and what is a good way of knowing it works, before buying it?
Compressor prices for brand new have come down significantly in the past few years; I would go that route rather than the time and effort to chance a used compressor. I see compressors as low as $230 at RockAuto
https://www.rockauto.com/en/catalog/hyu ... essor,6628
That said: about 25 years ago when I was poorer and before Internet, the AC compressor on our 1984 Jeep Cherokee seized and I did purchase a used one for $75. I'm in Arizona, figure most vehicles had working AC when wrecked, and new were about $700 then. That was removed from a Jeep while I was there, I installed it same day, R-12. That Jeep had manual AC shut off valves, so was able to isolate and save most of the R-12.
. I am going to need a/c gauges, please recommend me a brand/model 
. Also, days before it quit I could hear a metallic crushing noise associated with the a/c been turned on, and would go away when turn off (meanwhile the a/c was still blowing cold). Now, assuming the compressor is the problem. What do you guys think of using a compressor from a junkyard and what is a good way of knowing it works, before buying it?