Town & Country V6-3.8L VIN L (2006)
Radiator Cooling Fan Motor Relay: Description and Operation
RADIATOR FAN RELAY
DESCRIPTION
Fig. 39 Radiator Fan Relay
The radiator fan relay is a solid state type and is located on the front bumper reinforcement (Fig. 39).
OPERATION
The solid state radiator fan relay is controlled by the Powertrain Control Module (PCM) by way of a Pulse Width Modulated (PWM) signal. The relay
control circuit supplies a 12 volt signal to the PCM. The PCM then pulses the ground circuit to achieve fan on time. The relay provides a voltage to
the fan motors which is proportional to the pulse width it receives from the PCM. The duty cycle ranges from 30% for low speed operation, then
ramps-up to 100% for high speed operation. This fan control system provides infinitely variable fan speeds, allowing for improved fan noise, A/C
performance, better engine cooling, and additional vehicle power.
To control operation of the relay, the PCM looks at inputs from:
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Engine coolant temperature
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A/C pressure transducer
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Ambient temperature from the body controller
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Vehicle speed
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Transmission oil temperature
The PCM uses these inputs to determine when the fan should operate and at what speed.