The following article discuss about 1991 Hyundai Sonata Cooling System Service and Troubleshooting manual. Herein you will find detail specification of the cooling system, description of each parts and components function, maintenance, service, repair and troubleshooting procedures of the Sonata. This service manual is divided into following sections General Specification, Cooling System, Radiator, Radiator and Fan Motor Assembly, Water Pump, Thermostat, Water Hose and Pipe, Water Temperature Gauge Unit and Sensor.