Operation - Chrysler PT Cruiser Service & Repair Manual

PT
RADIATOR FAN (Continued)

OPERATION

Non-Turbo
Radiator fan operation is control by the Powertrain
Control Module (PCM) with inputs from the temper-
ature of the coolant, which is sensed by the coolant
temperature sensor, and vehicle speed which is mea-
sured by the vehicle speed sensor. The PCM turns on
the fan through either the high or low speed fan
relay. The PCM provides a ground to the relay's con-
trol circuit. The fan relays are located in the Power
Distribution Center (PDC) (Fig. 27). Refer to the
label beneath the PDC cover for location of fan
relays.
Refer to Radiator Fan Operation Chart for fan
operation specifications. For fan circuit wiring dia-
grams, refer to WIRING DIAGRAMS.
Fig. 27 Power Distribution Center (PDC)
1 - PCM
2 - PDC
If the cooling fan is inoperative or a Diagnostic
Trouble Code (DTC) related to fan control has been
set, refer to the appropriate Powertrain Diagnostic
Information for diagnostic procedures.
ENGINE - 2.0/2.4L DOHC
RADIATOR FAN OPERATION CHART
Radiator Fan Control
Low Speed
A/C Off –vehicle speed < 70.8 km/h (44 mph)
Fan On: 96.6° C (206° F)
Fan Off: 92.7° C (199° F)
A/C Off –vehicle speed > 70.8 km/h (44 mph)
(until vehicle speed drops below 58 km/h (36
mph)
Fan On:
Fan Off:
A/C On –any vehicle speed
Fan On:
Fan Off:
Turbo
The variable speed radiator fan is controlled by the
Powertrain Control Module (PCM) by way of a Pulse
Width Modulated (PWM) signal. The duty cycle
ranges from 30% for low speed operation, then
ramps-up to 100% for high speed operation. This fan
control system provides
speeds, allowing for improved fan noise, A/C perfor-
mance, better engine cooling, and additional vehicle
power.
To control radiator fan operation, the PCM looks at
inputs from:
• Engine coolant temperature
• A/C pressure transducer
• Ambient temperature
• Vehicle speed
• Transmission oil temperature (automatic trans-
mission only)
The PCM uses these inputs to determine when the
fan should operate and at what speed.
High Speed
103° C (219° F)
98.8° C (210° F)
103° C (219° F)
Off
98.8° C (210° F)
82.2° C (180° F)
Off
80° C (176° F)
infinitely variable
7 - 53
fan