no high pressure rv2 help!

What year/ model we working on?

If it's a factory system, did you read the shop manual?

Is it a system you put together from parts, and did it ever work (previously)?

What is the ambient temperature, and where are you located?

What is "temerature inside?" (25*) Inside the shop? Inside the car? probe stuck in the evap fins? 25F or 25C?

Did you try blocking the condenser to raise head pressure?

What makes you think the system is not "low on Freon?"

Are you using a PROPER R-12 refrigerant or are you using one of these aftermarket "fake" R12 mixes with propane or lipstick or some other unknown chemical added?