Two separate problems. The engine radiator fan permanently on might be because the temp sensor/sender switch has jammed, in which case you need to unscrew it from the block and fit another one (you'll need a big socket). Or it's because the cables to the fan itself are crossed so that the fan gets continuous power.

The a/c failure might be the a/c pump electromagnetic clutch or it might be the pump itself. That's a job for an a/c specialist to first make sure the system is fully gassed, because if it isn't it could be that the condenser radiator is holed or you're getting as leak somewhere else.