AC Discharge

radensb

Im looking to start work on replacing the gallery gaskets and decided to remove the radiator support to get full access to the area. To do this, the AC condenser needs to be removed and thus, the refrigerant needs to be recovered. I have an AC gauge set and decided to check the High and Low side pressure (which I expected to be in spec as the AC has always worked and ran fine last summer). I was surprised to see that the gauges read 0 PSI for both High and Low sides. Immediately thinking there was an issue with my Schrader valve openers or the gauges themselves, I poked a flat hex bit on the Schrader valve stem on both High and Low sides and it went down with only return spring resistance and nothing came out.

Am I missing something here? How can the AC have been working for a decade up to and including last summer without issue (blowing cold air) and now conveniently empty when I check it today??

Obviously, I don't want a 200PSI surprise when I remove the condenser but this has me puzzled.

Thoughts??
Thanks!