Problem: AC wont blow cold.

Found issues: Upon start up from a long period of down time(4 hours). The clutch will run for awhile cold air will blow then it will stop running and may or may not kick back on intermittently.

I think I have either high pressure or a bad high pressure sensor. I checked the refrigerant and it looked a little high after revving the engine. I released some R-134a. The clutch will engage for a longer period now but it still stops working shortly after taking off down the road.

Questions:
Could this be a high pressure issue?
If it is a high pressure sensor will I have to recover the R-134a, AKA will the R-134a leak out when I remove the sensor?