Engine Cooling Fan Chevrolet Caprice Impala SS

DESCRIPTION

Several descriptions of the cooling system and fans follow.

Overview

Three different cooling system options are available

1. Base cooling system
2. Extra-capacity cooling system ("V03")
3. Heavy-duty cooling system ("V08")

Each system has a different cooling fan arrangement. See COOLING FAN OPTIONS table for a summary of all the fan configurations. (Scheme 1)for a view of the different fan configuration.

The following text provides a high-level overview of each type of available cooling system.

Base Cooling System

The base version consists of an aluminum core with plastic end tanks radiator, a pressurized coolant recovery reservoir, an engine water pump driven by the camshaft gear (not by the drive belt), thermostat, and two-electric motor-driven fans. The right-hand end tank of the radiator contains a transmission oil cooler.

Extra-Capacity Cooling System

The extra-capacity cooling system ("V03") has the same components except that the left-hand electric motor-driven fan has a larger size motor and the left-hand end tank of the radiator is larger to allow for an engine oil cooler provided within that end tank.

Heavy-Duty Cooling System

The heavy-duty cooling system ("V08") has the same components as the extra-capacity cooling system except that the right-hand electric motor-driven cooling fan is replaced by a belt-driven hydraulic clutch-controlled fan. The coolant hoses connecting the engine to the radiator on the heavy duty cooling system have metal sections for protection from the belt-driven fan blades.

OPERATION

The operation of several subsystems are described below.

The electric cooling fan(s) are controlled by the PCM. The PCM controls the ground path for the cooling fan relay(s).

The relay(s) are used to control the high current flow to power the cooling fan motors. The PCM determines operation of the independent fans base on various sensor inputs.

Primary Cooling Fan

The primary cooling fan is controlled by the PCM based on inputs from the A/C system, Engine Coolant Temperature (ECT) sensor, Vehicle Speed Sensor (VSS).

The PCM will turn the primary cooling fan ON when any of the following conditions exist at idle

1. Certain PCM Diagnostic Trouble Codes (DTCs) set.
2. ECT above 225°F (107°C)
3. A/C head pressure above 189 PSI.

Once the primary fan has been turned ON by the Engine Coolant Temperature (ECT) sensor, the PCM will turn the fan OFF when that temperature has dropped about 7°F (4°C). If the primary cooling fan has been turned ON by high A/C head pressure, the PCM will turn the fan OFF when the pressure has dropped to 150 PSI. The minimum ON time for the primary cooling fan is 50 seconds.

Secondary Cooling Fan

The secondary cooling fan is controlled by the PCM based on inputs from the A/C system, Engine Coolant Temperature (ECT) sensor, Vehicle Speed Sensor (VSS).

The PCM will turn the secondary cooling fan ON when any of the following conditions exist at idle

1. Certain PCM Diagnostic Trouble Codes (DTCs) set.
2. ECT above 232°F (111°C)
3. A/C head pressure above 240 PSI.

Once the secondary fan has been turned ON by the Engine Coolant Temperature (ECT) sensor, the PCM will turn the fan OFF when that temperature has dropped about 7°F (4°C). If the primary cooling fan has been turned ON by high A/C head pressure, the PCM will turn the fan OFF when the pressure has dropped to 210 PSI. The minimum ON time for the primary cooling fan is 26 seconds.

Note. Vehicles equipped with the heavy-duty cooling system ("V08"), will have one mechanical fan (primary) and one electric fan (secondary).

COOLING FAN OPTIONS (1)

Scheme 1

FUNCTIONAL CHECK & TESTING

To check for proper functioning of the cooling fan(s), proceed to the following C-12 Chart. This chart will also lead you through any diagnosis necessary to troubleshoot faults found with the system.

Chart C-12, Electric Cooling Fan Circuit Diagnosis

Cooling fans are controlled by Powertrain Control Module (PCM) based on various inputs. Battery voltage is supplied to terminal C4 of primary fan relay and terminal C1 of secondary fan relay. Ignition voltage is supplied to terminal B4 of primary fan relay and terminal B1 of secondary fan relay. Grounding circuit No. 335 will energize primary cooling fan relay and supply battery voltage to primary cooling fan motor. Grounding circuit No. 473 will energize secondary cooling fan relay and supply battery to secondary cooling fan motor. (Scheme 2)for wiring diagram. When certain Diagnostic Trouble Codes (DTC) are set, PCM will energize cooling fans.

Scheme 2

Note. Test numbers refer to numbers on diagnostic charts. (Scheme 3)and (Scheme 4).

Scheme 3

Scheme 4

1. With output/field service enable terminal grounded at DLC, cooling fan control driver(s) will close, energizing fan control relay(s).
2. Cooling fans should come on anytime A/C system is operating. Engine coolant temperature must be less than 212°F (100°C) when performing this step.
3. Comparing Tech 1 scan tester pressure and manifold gauge set pressure will determine if A/C refrigerant pressure sensor is out of range. An out-of-range A/C pressure sensor can cause cooling fans to operate at the wrong times.

Diagnostic Aids for Chart C-12

1. Determine whether problem is an actual boilover, warning light or coolant temperature gauge malfunction. Using Tech 1 scan tester, check gauge accuracy by comparing Engine Coolant Temperature (ECT) sensor with gauge indication.
2. If engine is actually overheating and gauge indicates overheating, but cooling fans are off, ECT sensor has probably shifted out of calibration and should be replaced. If engine is overheating and cooling fans are on, check cooling system.
3. Primary cooling fan should come on at 225°F (107°C) and go off at 217°F (103°C). Secondary cooling fan should come on at 232°F (111°C) and go off at 224°F (107°C).

ELECTRICAL COMPONENT LOCATION

Note. For locations of components not listed and for terminal identification, see the wiring diagram, Fig. (Scheme 5).

COOLING FAN RELAY LOCATION

Cooling Fan Circuit Wiring Diagram. Scheme 5

See also:
• COOLING FAN OPTIONS