Testing an A/C vacuum switch
 

What is the right method to test an A/C vacuum switch? What does success and/or failure look like, exactly? I'm using a hand vac pump (made for bleeding brakes) on port 1 and plugging port 2 and 3 simultaneously, then checking to see if it can hold a static vacuum up to 15inHg. I'm clocking the switch in the positions it is in when installed in the A/C control head. I understand my method tests for vacuum sealing and not for whether it properly routes/releases vacuum to the right port (which it does do).

Back story: I bought a reconditioned 3-port unit that does not hold a vacuum at all per this test. This is the same result as the OEM 3-port unit I was hoping to replace. And those results are in contrast to an OEM 2-port unit I have that does successfully hold a vacuum. The seller of the reconditioned unit says I am testing it the wrong way and that the reconditioned unit tested fine when it shipped. I made a video and posted to YouTube (keep in mind the 2-port unit does not have a cap on port 2): https://youtu.be/DZZ7Emtmm-Y

What am I missing--how could it be acceptable to leak this much vacuum, regardless of whether it's downstream of a vacuum reservoir? Not interested in heeping scorn on the seller, just hoping to understand this part better so I can make sure I'm asking for the right things. I always learn a lot from the collective experience of this board.

Re: Testing an A/C vacuum switch
 

Did you resolve your A/C vacuum switch issue and get your A/C working properly?

I have a faulty A/C vacuum switch, and am trying to figure out where to go from here.

Re: Testing an A/C vacuum switch
 

Nope. My A/C quest keep stalling out every time I try to kickstart it. I haven’t found anything to change the theory of operation I spelled out below. And last I checked, the seller still believes this test result is fine.

Thanks for checking. Best of luck and do let us/me know if you get any answers on this.