When the system is static (clutch not engaged), you'll find that system pressure will be more or less equal to ambient temp in F. If you're reading 70psi, you're not engaging. Who knows why, but there is always the old standby of disconnecting the battery 15 minutes. The clutch is managed by computers, and every now and then a computer needs the old 3 finger salute. After you try that, go see the dealer.
And as always do not add refrigerant yourself. If a shop knows you did, they probably won't touch it for fear of getting their 3,000 to 10,000 dollar machine fucked up with sealant. You can never be sure your walmart refrigerant cans don't have "stop-leak". Quotes, because stop leak doesn't stop leaks, it fucks shit up.