He may be saying that his condensor fan was unplugged...look on the back of the fan, you'll see the plug, might be a tight fit, but check it out.

Well I guess you could try and trouble shoot the condensor fan. Test it by using wires directly on the battery. If that spins the motor, then start checking switches, wires, relays, fuses, etc.

You may need to recharge your AC system with new refrigerant. I know both my cars (97 and newer) both require 134A, not sure on your 90...I would assume it's 134A, but older cars require R12. If you ask at autozone, etc, they should be able to tell you. Just get a kit with a guage, etc, and follow the directions.