Q: How to diagnose and fix an overheating engine with a non-functioning cooling fan?
A: If the engine is overheating and the cooling fan is not coming on when the engine temperature rises, there are several steps to diagnose and potentially fix the issue. First, unplug the fan motor electrical connector and connect the motor directly to the battery with fused jumper wires. If the fan motor does not come on, it will need to be replaced. If the motor is okay, the problem may lie with one of the fan relays. There are three cooling fan relays that can be checked and replaced if necessary. If the relays are not the issue, the wiring and connections to the fan motor should be inspected. If no problems are found, the engine coolant temperature sensor or the Powertrain Control Module (PCM) may be the cause and should be diagnosed with proper equipment. To replace the cooling fan, the negative terminal of the battery should be disconnected and the vehicle securely supported. The lower splash pan, Radiator support cover, air filter housing, and torque strut (if equipped) should be removed. The coolant should be drained and the upper radiator hose and upper transaxle oil cooler line should be disconnected. If there is an oil cooler, the retaining bolt should be removed and the oil cooler lines disconnected. The fan electrical connectors and wiring harness should be disconnected, and the fan(s) lower mounting bolts should be removed. The fan(s) can then be unbolted from the radiator and carefully lifted out of the engine compartment. To detach the fan from the motor, the motor shaft nut should be removed, and to detach the fan motor from the shroud, the mounting bolts should be removed. Installation is the reverse of removal, and the cooling system should be refilled, the engine run, and checked for leaks and proper operation.