4
FIGURE 8
FAN PLATE
DUST SHIELD
PULLEY
THE TOTAL CHANGE IN THIS
DIMENSION FROM ITS
NARROWEST TO WIDEST
MEASUREMENT SHOULD
NOT BE 1/16” OR GREATER
Figure 7 depicts a combination of shutters, fan clutch and
air conditioning. This combination requires the two thermo-
pneumatic controls for fan and shutters, as well as the
electro-pneumatic override for the air conditioning. With this
combination the same requirements for fan control apply as
in Figure 5 and 6 with the additional requirement that the
shutters should be controlled in such a manner that they
always open whenever the air conditioning compressor
operates.
A variation of this combination consists of a two section
shutter with one section in front of the condenser and other
in front of the remaining portion of the radiator. In this
combination only the section in front of the condenser needs
to open when the air conditioner engages.
PREVENTIVE MAINTENANCE
There is no need for periodic maintenance; however, the
following service checks should be made to ensure proper
function of the fan clutch.
GENERAL
The condition of the two fan plate ball bearings should be
checked at regular intervals to ensure proper operation of
the FD-L
™
fan clutch. The procedure presented here is
intended to check excessive bearing play by measuring
lateral movement of the fan plate relative to the edge of the
pulley or a scribed line on the lining surface, when air is
applied.
CHECKING PROCEDURES
1. Park the vehicle on a level surface and block the wheels.
2. Shut off the engine and apply a minimum of 85 psi to
the fan clutch to disengage it. NOTE: If air brake system
pressure is above 85 psi and the engine is cool, the
FD-L
™
fan clutch will be disengaged. Disengagement is
confirmed by noting that the fan can be rotated freely by
hand. DO NOT PERFORM THIS CHECK WITH ENGINE
RUNNING.
3. With the engine off and the FD-L
™
fan clutch disengaged,
grasp the tip of one blade using only the thumb and
index finger. (Refer to Figure 8). Using a moderate force,
rock the fan blade back and forth toward the radiator
and measure the total movement of the fan plate relative
to the edge of the pulley. Replace or repair the fan
clutch if the total movement of the fan plate is 1/16" or
greater.
LINE HAUL VEHICLES
Every 50,000 miles, 1,800 hours, or every six months,
whichever occurs first, perform the service checks out lined
in this manual.
CITY DELIVERY
Every 15,000 miles, 300 hours or two months, whichever
occurs first, perform the service checks outlined in this
manual.
SERVICE CHECKS
Before performing the operational and leakage checks,
apply the vehicle parking brakes or chock the wheels.
OPERATIONAL
1. With the engine cold, the ignition off and at lease 85 psi
air pressure in the brake system, note that the fan is
disengaged from the pulley and can be turned by hand.
If the fan can be turned, proceed to Step #2. If it cannot
be turned:
A. Drain all reservoirs and disconnect the air control
line leading to the fan clutch and apply at least 85
psi shop air pressure to the fan clutch.
B. If the fan cannot be turned, the clutch is defective
and must be repaired or replaced (see appropriate
section of this manual).
C. If the fan can now be turned, check the air lines
leading to and from the thermostatic control valve for
“kinks” or obstructions, and check the control valve
itself according to the manufacturer’s instructions.
