3
FIGURE 5
FIGURE 7
FIGURE 8
FIGURE 6
the fan control, causing the fan to engage. Most vehicles
also have an additional dual function pressure switch
connected in series with the air conditioner clutch. This
switch is normally open, closes at approximately 30 P.S.I.
and opens again at approximately 400 P.S.I. Its purpose is
to prevent operation of the air conditioning compressor if
the refrigerant is lost or to shut off the compressor if the
system pressure reaches a dangerously high pressure
(approximately 400 P.S.I.). This switch does not normally
have anything to do with fan operation; however, it is
sometimes combined with the previously mentioned override
switch.
Figure 8 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 6 and 7 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 the
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
The durability of the Bendix
®
FD-1
™
fan clutch matches that
of the vehicle’s engine when proper maintenance is
performed. Maintenance intervals for the FD-1
™
clutch will
vary in relation to the type of service the vehicle performs.
The following is a guide:
THERMO-PNEUMATIC
VALVE
THERMO-PNEUMATIC
VALVES
BLOCK
FAN
CLUTCH
RADIATOR
RADIATOR
FAN
CLUTCH
BLOCK
SHUTTER
BLOCK
BLOCK
THERMO-PNEUMATIC
VALVE
THERMO-PNEUMATIC
VALVES
FAN
OVERRIDE
SWITCH
AIR
CONDITIONING
SIGNAL
AIR COND.
COMPRESSOR
SOLENOID
VALVE
FAN
CLUTCH
RADIATOR
CONDENSER
RECEIVER
DRYER
AIR
CONDITIONING
OVERRIDE
SWITCH
FAN
CLUTCH
RADIATOR
SHUTTER
SOLENOID VALVE
(NORMALLY OPEN)
AIR
CONDITIONING
SIGNAL
AIR
CONDITIONING
OVERRIDE
SWITCH
FAN
OVERRIDE
SWITCH
RECEIVER
DRYER
CONDENSER
AIR COND.
COMPRESSOR
