I think there is a ground wire near the condenser that is only for the fan. Check if power and ground are reaching the fan plug. Or unplug it and connect fan motor to the battery with two test wires. If the motor has power but doesn't run, it is bad.

Lack of the fan IS the problem. Without the fan, the condenser overheats, causing excessive pressure which prevents the system from cooling, also the pressure switch cuts the compressor off to keep the hoses from blowing out.