Low side shrader not opening. Make and model of vehicle?

By any chance is your lo0w side hose fitting not opening the low side shrader?

Try using a screwdriver handle and tap the clutch plate. See if it engages. If so, you have the well known gap problem.

Do not use soap and water. You will get better results using Big Blue or Snoop.

Keep the POA and expansion valve set up. All driers made now can handle r134a. I personally would keep it R12 also.

When not running, the system is equalized meaning both hi and lo side PSI are the same. The lo side gauge does not indicate the same PSI as the hi side so the lo side pegs. Perfectly normal.

I don't have a way to charge it. Need to take to the shop and they can't get to it until the first week in Aug. Yes you do have a way to charge it. Two hours of running a vacuum is not overkill. That system was open for a long time. If the pump usage doesn't cost you anything, let it run a long tim...

Those venture pumps are a POS. If you're waiting a week or so, pull the best vacuum you can and place the system under positive pressure.

Hot wire the fans to 12volts as a test. As soon as the key is turned, the fans come on.

I have never seen brass caps for R134a either factory or replacement. You can get them for R12 systems thru HVAC supply stores.