ELECTRICAL
10.29
OIL COOLER FAN CONTROL
SThermistor resistance decreases as temperature increases
SBoth fan and hot light should be on with thermistor leads shorted together (low resistance)
SFan blade should rotate drawing air in through cooler (blowing on engine)
THERMISTOR RESISTANCE VS. TEMPERATURE
Temperature Resistance
r
20% Fan ON/OFF Hot Light ON/OFF
77q F(25q C) 100K: Fan OFF
240q F(116q C) 3.5K: Fan OFF Temp Falling
260q F (127q C) 2.5K: Fan ON Temp Rising
290q F (143q C) 1.6K: Fan ON Hot Light ON/OFF
THERMISTOR / LR60 FAN CONTROL TEST
STurn ON and engine stop switch to RUN.
STest voltage on R/W wire to ground - R/W wire should have 12 Volts DC (battery voltage)
SShort thermistor leads together - fan and hot light ON? (If not, test hot light, fan motor and circuit)
SDisconnect thermistor wires and test the resistance of the thermistor (refer to temperature/resistance
table). Replace thermistor if out of specified range.
SReplace LR60 and test system.
Battery Voltage
Oil Cooler Fan Circuit
Hot light and fan “on” with these
leads connected together
(Below Head
Lamp)
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