AC Discharge
 

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!

My A/C leaked down once back in 2020. Refill it, and it has never done it again.

Did it leak down to 0 PSI? Its weird how something like can happen once. I have a vacuum pump on the way to pull lines down to -30 PSI as if I were going to fill it back up and see if it holds. I figure that this was I will guarantee that the lines are actually discharged and will see if I have a leak that I need to deal with after my gallery gasket repair. Then, when I am ready, I can just do my own charge and the equipment will pay for itself.

It got down to around 5 psi. Took 2 cans to fill it back up.

What is your mileage and results of the FSM oil pressure testing that required the galley gasket change?