Locate a truck with a Horton DriveMaster fan drive, preferably a make and model you would work on.

Locate the components listed below and answer the questions by filling in the corresponding blanks and checking the box next to the number when you complete a step. Upon completion, please check this activity with an instructor or supervisor.

1. Locate the DriveMaster fan drive and list the model.

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2. Locate the solenoid valve.

3. Locate the fan drive air filter (if equipped).

4. Locate the coolant temperature switch or sensor.

5. Locate the air-conditioning refrigerant pressure switch (if equipped).

6. Locate the fan drive manual override switch (if equipped).

7. How many belts are on the fan drive sheave?

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8. What engine components do the belts go around?

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9. How many bolts mount the fan drive to the engine?

10. Locate the air hose that supplies air to the solenoid.
Where does the hose attach to the air supply?

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11. Does the truck have an ECM?

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12. In the truck's service manual, locate the electrical diagram for the fan drive control solenoid and the ECM.

13. Draw the schematic symbol used in your truck's electrical diagram for each of the following components:

Solenoid Valve

Engine-Coolant Thermal Switch/Sensor

Air-Conditioning Refrigerant Pressure Switch/Sensor

Manual Override Switch

Learning Objective:
• Locate and identify components of the fan drive system.

• Interpret the vehicle's electrical diagram for various fan drive system components.

WARNING
For your safety, be sure the engine is off.