To determine if an inoperative thermo-modulated fan is causing high engine coolant temperature,
test the thermo-modulated fan; refer to OEM guidelines.
1. If the thermo-modulated fan is functioning correctly, check thermostats; refer to section
13.7.
2. If the thermo-modulated fan is not functioning correctly, refer to section 13.6.1.
13.6.1
Thermo-modulated Fan Replacement
Perform the following steps to replace inoperative thermo-modulated fan:
1. Replace inoperative thermo-modulated fan; refer to OEM guidelines.
2. Verify thermo-modulated fan replacement; refer to section 13.6.1.1.
13.6.1.1
Test Engine with Replaced Thermo-modulated Fan
Perform the following to determine if thermo-modulated fan replacement resolved high engine
coolant temperature:
1. Start and run the engine.
2. Run the engine through its operating range with no-load for approximately 5 minutes,
allowing the engine coolant to reach normal operating range.
[a] If the engine coolant temperature is 88-96°C (190-210°F), no further troubleshooting
is required. Shut down the engine.
[b] If the engine coolant temperature is not 88-96°C (190-210°F), shut down the engine.
Check thermostats; refer to section 13.7.
