Horton DriveMaster® Fan Clutch

cen mm 20.03.000

Note: If any part of the fan clutch needs to be repaired or replaced after performing the checks below, see of the Century Class Trucks Workshop Manual.

  1. Disconnect the batteries at the negative terminals. Drain all air from the air system. If equipped with an air starter, drain the air starter reservoir.

    2. Warning: Make sure the batteries are disconnected before checking the fan clutch. If the engine starts during this procedure, the fan could engage, which could result in serious personal injury.

  2. Inspect the electrical connections and wires to the fan clutch solenoid. Secure the connection if loose; replace wires and connectors if damaged.
  3. Clean the fan clutch air solenoid valve filter, if equipped.
    1. Unscrew the fan clutch solenoid valve air filter assembly and remove the filter element.
    2. Clean the filter element with cleaning solvent.
    3. Using a clean, lint free cloth, wipe off any excess solvent.
    4. Reassemble the clutch valve solenoid air filter assembly and install on the vehicle.
  4. Visually check the fan for bent, cracked, or damaged blades. Replace if damaged. Check for adequate clearance between the fan and other components.
  5. Check the fan belt for wear, tension, and alignment. Correct, if necessary.
  6. Check for wear on the friction facing. Replace the friction facing if it is worn to a 3/16-inch (4.8-mm) thickness or less. Also check the facing for signs of oil contamination or burn marks. If evidence of oil or burn marks are found, replace the friction facing.
  7. Connect the battery cables. Start the engine, and charge the air system to 120 psi (827 kPa). Manually engage and disengage the fan clutch.
    Check the fan and the fan clutch from a distance. Look for vibration, fan blade contact, fan clutch slippage, and overall fan clutch operation.
    If the fan clutch does not operate correctly, see of the Century Class Trucks Workshop Manual for troubleshooting and repair procedures.
  8. With the air system charged to 120 psi (827 kPa), check the fan clutch for audible air leaks, using a suitable listening device.
    Check at the solenoid valve, the air filter assembly, and the air hoses and fittings. See Fig.. Using a wet finger or a soapy water solution, check for a leak in the same areas.

    Fig. 1, Checking for Air Leaks (Horton DriveMaster)

  9. If a leak is detected, remove the fan blade. Install a new seal kit. See of the Century Class Trucks Workshop Manual for repair procedures.
  10. Check the fan drive for discoloration or any other signs of slipping or overheating.

    11. Note: The fan clutch may slip if the air supply pressure is below 70 psi (483 kPa) or if there is a leak inside the fan clutch. Any leak must be remedied.

  11. Check the fan clutch bearings.
    1. Turn the fan in both directions and feel for worn hub bearings.
    2. If possible, remove the drive belt and check for worn sheave bearings by turning the sheave in both directions.
    3. If either the hub or sheave bearings are worn, replace them, using a Horton DriveMaster Super Kit.
      For instructions and kit part number, see of the Century Class Trucks Workshop Manual.
Note:
Parent topic: Fan Clutch Check (Noise Emission Control)
Document Number: 0000121900
Manual Publication Date: 2025-02-11
Topic Publication Date: 2024-06-04