In order to verify the fan operation, place a jumper wire between the fan test terminal and ground terminal of the diagnosis connector on the engine compartment firewall. The fan is supposed to run with ignition key ON, and in case it does not, check the components of the fan system such as a fan relay, thermoswitch, and motor. In the case of an inoperative fan motor, one should first clear the fuses, and then remove the electrical connector at the fan motor and should connect the fan to the battery using fused jumper wires. In case the fan fails to operate, change it particularly when it is two speed fan, making sure both are tested. When the fan motor test is found to be all right, but still inoperative, the problem could be with the fuse, relays, thermoswitch, or or wiring and relays and thermoswitch can be tested to determine continuity. The fan thermoswitch should have no continuity with cold and continuity with hot on 1990 through 1994 models. In the case of two-speed fan models, the second thermoswitch ought to be tested as well in the same manner. Find the number 1 fan relay in the main relay box and check continuity, remembering to check the appropriate terminal guides in accordance with model year. In case all components test good, additional diagnosis could be required at a repair facility of a qualified institution. To change the fan, disconnect negative battery cable, drain cooling system and then remove the resonance chamber, wiring connector on the fan motor, upper radiator hose, unbolt and lift fan shroud then remove fan retaining nut and fan on the motor. Lastly, take out the fan motor of the shroud and replace everything in the opposite order ensuring that all the bolts are tightened.