TM 9-2320-363-20-1
Section 4
TROUBLESHOOTING CHARTS
D. CHART 25 - FAN CONTROL MALFUNCTION (Cont'd)
Two Separate Fans
This configuration uses two digital outputs, Fan Control 1 and Fan Control 2, to drive two separate fans. Table 1 shows
the input and output states during fan operation. Fan Control 1 and Fan Control 2 are opened to turn each respective fan
"on". Fan Control 1 and Fan Control 2 are switched to battery ground to turn each respective fan "off'.
Fan Control 1 is enabled (opened) when at least one of the following conditions occurs.
1.
Air temperature above 49 C
2.
Air conditioner is active (OEM supplied A/C switch is opened)
3.
Air temperature sensor fails
4.
Fan engine brake enable and the engine brake is active at "High" Level.
5.
Fan control override switch is enabled.
6.
Pressure governor system is active.
Fan Control 2 is enabled (switch to battery ground) when at least one of the following conditions occur.
1.
Oil temperature above 114 C
2.
Coolant temperature above 96 C
3.
Oil temperature sensor fails
4.
Coolant temperature sensor fails
Note: The temperature values used above are default values. These values can be changed at the time of
engine order.
Two Speed Fan
The third configuration uses two digital outputs, Fan Control 1 and Fan Control 2, to drive a two speed fan. Table 1 shows
the input and output states during fan operation. When Fan Control 1 output is opened, the low speed fan mode
activates. The fan operates in the high speed mode, if Fan Control 2 output is opened. When the fan is operating in the
high speed mode (Fan Control 1) whenever the engine RPM is greater than 1500 RPM. Fan Control I is disabled when
Fan Control 2 is enabled.
1.
Oil temperature above 111 C
2.
Coolant temperature above 90 C
3.
Air temperature above 49 C
4.
Air conditioner is active (OEM supplied A/C switch is opened)
5.
Oil temperature sensor fails
6.
Coolant temperature sensor fails
7.
Air temperature sensor fails
8.
Dynamic engine brake enable and engine brake level is "high".
9.
Fan control override switch is enabled
10.
Pressure governor system is active,
Fan Control 2 is enabled (opened) when at least one of the following conditions occur.
1.
Oil temperature above 114 C
2.
Coolant temperature above 96 C
Note: The temperature values used above are default values. These values can be changed at the time of
engine order.
Change 3 3-345.171
