It’s sound like it’s low on refrigerant. Could be your AC relay going bad in the fuse box under the hood also. My AC clutch was acting flakey recently and then just stopped working altogether so I got a new relay from the dealership for $4.00 and the clutch turned on instantly when I turned on the AC. Maybe you have 2-3 problems going on atthe same time. Flakey relay and low refrigerant. Me psersonally, to fix your situation, i would put in a new relay, relieve and vacuum the system down to 30Hg, turn the vacuum pump off and let it sit like for an entire hour with your manifold gauge attached and see if tge vacuum holds and there’s no leaks. If you got a leak, cheapest thing to do first is replace both the schrader valves in the high and low pressure ports then re-vacuum and see if it holds. If it holds add the amount of refrigerant according to tge sticker specs under the hood, no more and no less, no matter what your gauge reading say then see how she runs.
BEST detailed AC instructions out there right here:
https://ricksfreeautorepairadvice.co...auge-readings/
Other easily dooable things after you determine that: 1. There are no leaks 2. You have have the exact correct amount of refrigerant in the system and you still have a problem.
Replace orifice tube or expansion valve (whichever one you have)
Replace the accumulator and high pressure switch.
Also, you can check for blockages in the system via STATIC GAUGE READINGS. Go to that link and it will explain.
Harbor Freight manifold gauges and HF vacuum pump that will pull to 30Hg. Very good investment.