be inspected for play, roughness, or damage.
Hub bearing service kits are available from
Kysor.
7. Check the lining with the System Alert Tool
™
.If
the lining is worn, install the appropriate lining kit.
A lining that is prematurely worn is caused by
control air supply problems. Inspect and correct
the vehicle control system before placing the
vehicle back in service.
8. Check the air line entry and routing at the front
or rear of the fan drive. Look for cracked,
damaged, or improperly routed air lines. Make
sure the connections are tight and that there are
no air leaks.
9. Check the electrical connections at the solenoid
valve. The solenoid valve is part of the air
module unit (AMU), which is located on the rear
crossmember. Check the exhaust port for
restrictions. If a restriction is found, clear it.
Horton DriveMaster® Fan Clutch
NOTE: If any part of the fan clutch needs to be
repaired or replaced after performing the checks
below, see Group 20 of the Business Class®
M2 Plus 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.
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.
3.1 Unscrew the fan clutch solenoid valve air
filter assembly, and remove the filter
element.
3.2 Clean the filter element with cleaning
solvent.
3.3 Using a clean, lint-free cloth, wipe off any
excess solvent.
3.4 Reassemble the clutch valve solenoid air
filter assembly, and install it 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
Group 20 of the Business Class M2 Plus
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. 1. Using a wet finger or a soapy water
solution, check for a leak in the same areas.
9. If a leak is detected, remove the fan blade.
Install a new seal kit. See Group 20 of the
Business Class M2 Plus Workshop Manual for
repair procedures.
10. Check the fan drive for discoloration or any other
signs of slipping or overheating.
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.
Engine Cooling/Radiator 20
Business Class M2 Plus Maintenance Manual, 02/10/2023 20/3
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