Engine Cooling System Chevrolet Aveo I

Fastener Tightening Specifications

Fastener Tightening Specifications

Engine Cooling System Specifications

Scheme 1

Scheme 2

Scheme 3

Scheme 4

Scheme 5

Cooling System Connector End Views

Cooling Fan - Auxiliary Connector Part Information AMP 176146 2-way F 187 Series Seales Connector 2 Pos Plug Hsg Ass'y (BK) Pin Wire Color Circuit Number Function 1 L-BU 504 Cooling Fan Low Reference 2 BN 409 Cooling Fan Motor Supply Voltage

Cooling Fan - Main Connector Part Information AMP 176146 2-way F 187 Series Seales Connector 2 Pos Plug Hsg Ass'y (BK) Pin Wire Color Circuit Number Function 1 BK 150 Ground 2 PU 532 Cooling Fan Motor Supply Voltage

Diagnostic Starting Point - Engine Cooling

Begin the system diagnosis by reviewing the system Description and Operation. Reviewing the Description and Operation information will help you determine the correct symptom diagnostic procedure when a malfunction exists. Reviewing the Description and Operation information will also help you determine if the condition described by the customer is normal operation. Refer to Symptoms - Engine Cooling in order to identify the correct procedure for diagnosing the system and where the procedure is located.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 2: Lack of Communication may be due to a malfunction of the serial data circuits. The specified procedure will determine the particular condition.
2. 3: The presence of DTCs may be related to an engine cooling condition. The specified procedure will compile all the available information before tests are performed.

Diagnostic System Check - Engine Cooling

Circuit Description

The Cooling Fan Relay 1 and the Cooling Fan Relay 2 are controlled by the engine control module (ECM). Battery positive voltage is supplied to the relay coil. The ECM monitors the voltage level on the control circuit of the relay. When the relay is off, voltage level should be near battery voltage on the control circuit of the relay. When the relay is commanded on, voltage level will be low on the control circuit of the relay. The ECM will provide ground on the control circuit of the relay using a low side driver. If the ECM detects a improper voltage level on the control circuit of the relay, a DTC will set.

DTC Descriptor

This diagnostic procedure supports the following DTCs

1. DTC P0480 Cooling Fan Relay 1 Control Circuit
2. DTC P0481 Cooling Fan Relay 2 Control Circuit

Conditions for Running the DTC

1. The ignition is ON or the engine is operating.
2. The ignition 1 voltage is more than 10 volts.
3. DTCs P0480 and P0481 run continuously once the above conditions are met.

Conditions for Setting the DTC

The ECM detects one of the following conditions on the control circuit of one of the relays

1. An open
2. A short to ground
3. A short to voltage

Action Taken When the DTC Sets

1. The malfunction indicator lamp (MIL) will not illuminate.
2. The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.

Conditions for Clearing the MIL/DTC

1. DTCs can be cleared by using the scan tool.
2. Disconnect the ECM battery feed for more than 10 seconds.

Diagnostic Aids

1. For an intermittent condition, refer to «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/aveo/i-2003-2008/remont/electrical-component-locations/#wiring-systems-electrical-power-management__testing-for-intermittent-conditions-and-poor) in Wiring Systems.
2. The following tables illustrate the COOL FAN LOW relay and COOL FAN HIGH relay terminal locations in the underhood fuse block

DTC P0480 or P0481

DTC P0480 or P0481

The numbers below refer to the step numbers on the diagnostic table.

1. 6: A test lamp that remains illuminated indicates a short to ground on the control circuit. A test lamp that does not illuminate indicates an open or short to voltage on the control circuit.
2. 8: This step tests the control circuit for high resistance.

DTC P0480 or P0481

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «Cooling Fan Circuit Diagnosis (Single Fan)»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling Fan Circuit Diagnosis (Dual Fan)»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Engine Overheating»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system__engine-overheating)
3. «Loss of Coolant»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system__loss-of-coolant)
4. «Thermostat Diagnosis»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system__thermostat-diagnosis)
5. «Coolant Heater Inoperative»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system__coolant-heater-inoperative)
6. «Engine Fails To Reach Normal Operating Temperature»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system__engine-fails-to-reach-normal-operating)

The engine cooling fan circuit operates the cooling fan. The cooling fan is controlled by engine control module (ECM) based on input from the engine coolant temperature (ECT) sensor. The ECM controls the low speed cooling fan operation by providing a ground signal to the low speed fan relay. This energizes the low speed cooling fan relay and operates the cooling fan at low speed. The low speed cooling fan operation is achieved by the cooling fan resistor causing a drop in the voltage supplied to the cooling fan. The ECM controls the high speed cooling fan operation by providing a ground signal to the high speed fan relay. This energizes the high speed cooling fan relay, bypassing the radiator fan resistor. This results in high speed cooling fan operation.

1. If the owner complained of an overheating problem, it must be determined if the complaint was due to an actual boil over, or the engine coolant temperature gage indicated overheating. If the engine is overheating and the cooling fans are ON, the cooling system should be inspected.
2. If the I/P fuse block fuse F18 or the engine fuse block fuse EF3, become open, blown, immediately after installation, inspect for a short to ground in the wiring of the appropriate circuit. If the fuses become open, blown, when the cooling fan is to be turned ON by the ECM, suspect a faulty cooling fan motor.
3. The ECM will turn the cooling fans ON at low speed when the coolant temperature is 93°C (199°F). The ECM will turn the cooling fans OFF when the coolant temperature is 90°C (194°F).
4. The ECM will turn the cooling fans ON at high speed when the coolant temperature is 97°C (207°F). The ECM will change the cooling fans from high speed to low speed when the coolant temperature is 94°C (201°F).
5. The cooling fan circuit can be inspected quickly by disconnecting the ECM connector and grounding the low cooling fan control circuit. This should create low speed cooling fan operation with the ignition ON. By grounding the ECM low cooling fan relay and high cooling fan relay control circuits and turning the ignition ON, high speed cooling fan operation should be achieved.

The numbers below refer to the step numbers on the diagnostic table.

1. 4: This step, along with step 5, checks for the ability of the ECM to operate the cooling fans.
2. 22: By directly grounding the ECM low cooling fan relay and high cooling fan relay control circuits, the cooling fan should run at high speed.

Cooling Fan Circuit Diagnosis (Single Fan)

The engine cooling fan circuit operates the main cooling fan and the auxiliary cooling fan. The cooling fans are controlled by the engine control module (ECM) based on inputs from the engine coolant temperature (ECT) sensor and the air conditioning pressure (ACP) sensor. The ECM controls the low speed cooling fan operation by providing a ground signal to the low speed fan relay. This energizes the low speed cooling fan relay and operates the main cooling fan and the auxiliary cooling fan at low speed as the cooling fans are connected in a series circuit. The ECM controls the high speed cooling fan operation by providing a ground signal to the high speed cooling fan relay and the series/parallel relay a the same time. This energizes the low speed cooling fan relay, the high speed cooling fan relay, and the series/parallel cooling fan relay resulting in high speed fan operation as the cooling fans are now connected in a parallel circuit.

1. If the owner complained of an overheating problem, it must be determined if the complaint was due to an actual boil over, or the engine coolant temperature gage indicated overheating. If the engine is overheating and the cooling fans are ON, the cooling system should be inspected.
2. If the engine fuse block fuses EF3 become open, blown, immediately after installation, inspect for a short to ground in the wiring of the appropriate circuit. If the fuses become open, blown, when the cooling fans are to be turned ON by the ECM, suspect a faulty cooling fan motor.
3. The ECM will turn the cooling fans ON at low speed when the coolant temperature is 97°C (207°F). The ECM will turn the cooling fans OFF when the coolant temperature is 94°C (201°F).
4. The ECM will turn the cooling fans ON at high speed when the coolant temperature is 101°C (214°F). The ECM will change the cooling fans from high speed to low speed when the coolant temperature is 98°C (208°F).
5. The ECM will turn the cooling fans ON at low speed when the A/C system is ON. The ECM will change the cooling fans from low speed to high speed when the high side A/C pressure is 1882 kPa (273 psi), then return to low speed when the high side A/C pressure is 1448 kPa (210 psi). When the A/C system is ON, the ECM will change the cooling fans from low to high speed when the coolant temperature reaches 117°C (244°F), then return to low speed when the coolant temperature reaches 114°C (237°F).
6. The cooling fan circuit can be inspected quickly by disconnecting the ECM and ground the low speed relay control circuit. This should create low speed cooling fan operation with the ignition ON. By grounding the ECM low speed relay control circuit and the high speed relay control circuit and turning the ignition ON, high speed cooling fan operation should be achieved.

The numbers below refer to the step numbers on the diagnostic table.

1. 4: This step, along with step 5, checks for the ability of the ECM to operate the cooling fans.
2. 8: This step, along with step 9, checks for the ability of the ECM to operate the cooling fans in response to A/C pressure readings.
3. 16: After confirming battery voltage and the ECM supplying a ground to the coil side of the cooling fan relay A, by jumpering connector terminals 30 and 87, it will be determined if the relay is at fault or a wiring problem is present.
4. 31: This step checks for the presence of battery voltage to the main cooling fan when the A/C is ON. If battery voltage is present and the cooling fans are not operating, the problem is in the ground side of the cooling fan circuit.
5. 37: By directly grounding the ECM low relay and high relay control circuits, the main and auxiliary cooling fans should run at high speed.

Cooling Fan Circuit Diagnosis (Dual Fan)

Engine Overheating

Engine Overheating

Loss of Coolant

Loss of Coolant

Thermostat Diagnosis

1. Remove the thermostat from the vehicle. Refer to «Thermostat Replacement»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Make sure the valve spring is tight when the thermostat is fully closed. If the spring is not tight, replace the thermostat.
3. Suspend the thermostat and a thermometer in a pan of 50/50 mixture of ethylene glycol and water. Do not let the thermostat or the thermometer rest on the bottom of the pan because the uneven concentration of heat on the bottom could result in inaccurate temperature measurements.
4. Heat the pan on a burner.
5. Use the thermometer to measure the temperature of the heated solution.
6. The thermostat should begin to open at 87°C (189°F) and it should be fully open at 102°C (216°F). If it does not open at these temperatures, replace the thermostat.

Coolant Heater Inoperative

Coolant Heater Inoperative

Engine Fails To Reach Normal Operating Temperature

Engine Fails To Reach Normal Operating Temperature

Pressure Cap Testing

Tools Required

KM-471 Adapter. See Special Tools .

The surge tank cap maintains proper pressure, protects the system from high pressure by opening a pressure valve, and protects the coolant hoses from collapsing because of a vacuum.

1. Wash any sludge from the surge tank cap and the valve seat of the vacuum pressure valve for the surge tank cap.
2. Check for any damage or deformity to the vacuum pressure valve for the surge tank cap. If any damage or deformity is found, replace the cap.
3. Install a suitable cooling system pressure tester to the cap using the KM-471 . See «Special Tools»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
4. Pull the vacuum pressure valve open. If the surge tank cap does not seal properly, replace the surge tank cap.
5. Pressurize the cap to 120-160 kPa (17-23 psi).
6. Wait 10 seconds and check the pressure held by the tank cap tester.
7. If the pressure held by the cooling system pressure tester falls below 80 kPa (16 psi), replace the surge tank cap.

Draining and Filling Cooling System

1. Place a pan below the vehicle to catch the draining coolant.
2. Remove the surge tank cap.
3. Unplug the drain cock.
4. Catch the escaping fluid in a drain pan.
5. Remove all sludge and dirt from inside the surge tank. Refer to «Surge Tank Replacement»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system) .
6. Plug the drain cock.
7. Add clean water to the surge tank.
8. Fill the tank slowly so that the upper reservoir hose remains above the water line. This allows the air inside the cooling system to escape.
9. Start the engine.
10. Run the engine until the thermostat opens. You can tell the thermostat is open when both radiator hoses are hot to the touch.
11. Stop the engine.
12. Repeat steps 1-9 until the drained water is clear and free of coolant and rust.
13. Fill the cooling system through the surge tank with a mixture of ethylene glycol antifreeze and water. The mixture must be at least 50 percent antifreeze, but not more than 60 percent antifreeze for cold weather operation.
14. Fill the surge tank to the specified MAX fill mark on the outside of the tank.

Removal Procedure

1. Disconnect the negative battery cable.
2. Drain the coolant. Refer to «Draining and Filling Cooling System»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system) .
3. Remove the rear timing belt cover. Refer to «Timing Belt Cover Replacement»(ref-196120-S16734477672005100600000) in Engine Mechanical 1.6L.
4. Remove the coolant pump mounting bolts.
5. Remove the coolant pump.
6. Remove the seal ring from the coolant pump.

Installation Procedure

1. Install a new seal ring to the coolant pump.
2. Coat the sealing surface of the seal ring with Lubriplater®.
3. Install the coolant pump to the engine block with the flange aligned with the recess of the rear timing belt cover. NOTE: Refer to «Fastener Notice»(/chevrolet/aveo/i-2003-2008/remont/oem-general-information/#cautions-and-notices__fastener-notice) in Cautions and Notices.
4. Install the coolant pump mounting bolts. Tighten: Tighten the coolant pump mounting bolts to 10 N.m (89 lb in).
5. Install the rear timing belt cover. Refer to «Timing Belt Cover Replacement»(ref-196120-S16734477672005100600000) in Engine Mechanical 1.6L.
6. Fill the engine cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system) .
7. Connect the negative battery cable.

1. Drain the engine coolant to below the level of the surge tank.
2. Loosen the overflow hose clamps and disconnect the overflow hose from the top of the surge tank.
3. Remove the tank attaching nuts.
4. Remove the tank from the vehicle.
5. Clean the inside and the outside of the surge tank and the surge tank cap with soap and water.
6. Rinse the surge tank and the cap thoroughly.

1. Install the surge tank to the vehicle.
2. Secure the surge tank with the attaching nuts. Tighten: Tighten the surge tank attaching nuts to 10 N.m (89 lb in).
3. Connect the overflow hose to the surge tank.
4. Secure the overflow hose to the surge tank with the hose clamps.
5. Fill the surge tank with the coolant to the center ridge, or to the MAX mark.

1. Disconnect the negative battery cable.
2. Disconnect the cooling fan electrical connector(s).
3. Remove the electric cooling fan mounting bolts.
4. Remove the electric cooling fan.

1. Install the electric cooling fan(s).
2. Install the electric cooling fan mounting bolts. Tighten: Tighten the electrical cooling fan mounting bolts to 4 N.m (35 lb in).
3. Connect the cooling fan electrical connector.

1. Drain the coolant. Refer to «Draining and Filling Cooling System»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system) .
2. Disconnect the upper radiator hose from the thermostat housing.
3. Disconnect the throttle body coolant inlet hose from the thermostat housing.
4. Remove the thermostat bolts.
5. Remove the thermostat housing.
6. Remove the thermostat with the gasket.
7. Inspect the gasket for cracks or other damage.
8. Inspect the valve seat for foreign matter that could prevent the valve from seating properly.
9. Inspect the thermostat for proper operation. Refer to «Thermostat Diagnosis»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system__thermostat-diagnosis) .

1. Install the thermostat with the bolts and the thermostat housing. Tighten: Tighten the mounting bolts to 20 N.m (15 lb ft).
2. Secure the upper radiator hose to the thermostat housing with a hose clamp.
3. Connect the throttle body coolant inlet hose to the thermostat housing.
4. Refill the engine cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system) .

1. Disconnect the negative battery cable.
2. Drain the engine cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system) .
3. Remove the electric cooling fans. Refer to «Cooling Fan Replacement - Electric»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Remove the upper radiator hose clamp.
5. Disconnect the upper radiator hose from the radiator.
6. Disconnect the lower radiator hose from the radiator.
7. Remove the lower radiator hose clamp.
8. Remove the hose clamp from the surge tank hose at the radiator.
9. Disconnect the surge tank hose from the radiator.
10. Remove the left upper radiator retaining bolt.
11. Remove the left upper radiator retaining bracket.
12. Remove the right upper radiator retaining bolt.
13. Remove the right upper radiator retaining bracket.
14. Remove the radiator from the vehicle.

1. Set the radiator into place in the vehicle with the radiator bottom posts in the rubber shock bumpers.
2. Position the radiator retainers in place.
3. Install the upper right radiator retaining bracket.
4. Install the upper right radiator retaining bolt. Tighten: Tighten the upper right radiator retaining bolt to 7 N.m (62 lb in).
5. Install the upper left radiator retaining bracket.
6. Install the upper left radiator retaining bolt. Tighten: Tighten the upper left radiator retaining bolt to 7 N.m (62 lb in).
7. Connect the surge tank hose to the radiator.
8. Secure the surge tank hose with a hose clamp.
9. Connect the upper radiator hose and the lower radiator hose to the radiator.
10. Secure each hose with a hose clamp.
11. Install the electric cooling fans. Refer to «Cooling Fan Replacement - Electric»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system) .
12. Refill the engine cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system) .
13. Connect the negative battery cable.

1. Drain the cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system) .
2. Disconnect the coolant heater power supply cord from the coolant heater.
3. Remove the coolant heater and seal from the engine block.

1. Install the seal to the coolant heater.
2. Install the coolant heater in to the engine block. Tighten: Tighten the coolant heater to 60 N.m (44 lb ft).
3. Connect the coolant heater power supply cord to the coolant heater.
4. Fill the cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/aveo/i-2003-2008/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system) .

Coolant Heater Cord Replacement

1. Disconnect the coolant heater power supply cord from the coolant heater (2).
2. Disconnect the coolant heater cord clip (1) from the engine lift bracket.
3. Disconnect the coolant heater cord from between the washer bottle and the coolant reservoir (1).
4. Remove the coolant heater cord from the vehicle.

1. Connect the coolant heater cord to the coolant heater (2).
2. Secure the coolant heater cord clip (1) to the engine lift bracket.
3. Route the coolant heater cord along the battery (2).
4. Secure the coiled power cord between the washer fluid bottle and the coolant reservoir (1).

Cooling System Description and Operation

The cooling system maintains the engine temperature at an efficient level during all engine operating conditions. When the engine is cold, the cooling system cools the engine slowly or not at all. This slow cooling of the engine allows the engine to warm up quickly.

The cooling system includes a radiator and recovery subsystem, cooling fans, a thermostat and housing, a coolant pump, and a coolant pump drive belt. The timing belt drives the coolant pump.

All components must function properly in order for the cooling system to operate. The coolant pump draws the coolant from the radiator. The coolant then circulates through water jackets in the engine block, the intake manifold, and the cylinder head. When the coolant reaches the operating temperature of the thermostat, the thermostat opens. The coolant then goes back to the radiator where it cools.

This system directs some coolant through the hoses to the heater core. This provides for heating and defrosting. The surge tank is connected to the radiator to recover the coolant displaced by expansion from the high temperatures. The surge tank maintains the correct coolant level.

The cooling system for this vehicle has no radiator cap or filler neck. The coolant is added to the cooling system through the surge tank.

Radiator

This vehicle has a lightweight tube-and-fin aluminum radiator. Two models of radiators are available: small, standard, and heavy duty. The 2 models vary only by capacity. Plastic tanks are mounted on the right and the left sides of the radiator core.

On vehicles equipped with automatic transaxles, the transaxle fluid cooler lines run through the left radiator tank. A radiator drain cock is on this radiator.

To drain the cooling system, open the drain cock.

Surge Tank

The surge tank is a transparent plastic reservoir, similar to the windshield washer reservoir.

The surge tank is connected to the radiator by a hose and to the engine cooling system by another hose. As the vehicle is driven, the engine coolant heats and expands. The portion of the engine coolant displaced by this expansion flows from the radiator and the engine into the surge tank. The air trapped in the radiator and the engine is degassed into the surge tank.

When the engine stops, the engine coolant cools and contracts. The displaced engine coolant is then drawn back into the radiator and the engine. This keeps the radiator filled with coolant to the desired level at all times and increases the cooling efficiency.

Maintain the coolant level between the MIN and the MAX marks on the surge tank when the system is cold.

Coolant Pump

The belt-driven centrifugal coolant pump consists of an impeller, a drive shaft, and a belt pulley. The coolant pump is mounted on the front of the transverse-mounted engine, and is driven by the timing belt.

The impeller is supported by a completely sealed bearing.

The coolant pump is serviced as an assembly and, therefore, cannot be disassembled.

Thermostat

A wax pellet-type thermostat controls the flow of the engine coolant through the engine cooling system. The thermostat is mounted in the thermostat housing to the front of the cylinder head.

The thermostat stops the flow of the engine coolant from the engine to the radiator to provide faster warm-up, and to regulate the coolant temperature. The thermostat remains closed while the engine coolant is cold, preventing circulation of the engine coolant through the radiator. At this point, the engine coolant is allowed to circulate only throughout the heater core to warm it quickly and evenly.

As the engine warms, the thermostat opens. This allows the engine coolant to flow through the radiator where the heat is dissipated through the radiator. This opening and closing of the thermostat permits enough engine coolant to enter the radiator to keep the engine within proper engine temperature operating limits.

The wax pellet in the thermostat is hermetically sealed in a metal case. The wax element of the thermostat expands when it is heated and contracts when it is cooled.

As the vehicle is driven and the engine warms, the engine coolant temperature increases. When the engine coolant reaches a specified temperature, the wax pellet element in the thermostat expands and exerts pressure against the metal case, forcing the valve open. This allows the engine coolant to flow through the engine cooling system and cool the engine.

As the wax pellet cools, the contraction allows a spring to close the valve.

The thermostat begins to open at 87°C (189°F) and is fully open at 102°C (216°F). The thermostat closes at 86°C (187°F).

Electric Cooling Fan

The cooling fans are mounted behind the radiator in the engine compartment. The electric cooling fans increase the flow of air across the radiator fins and across the condenser on A/C-equipped vehicles. This helps to speed cooling when the vehicle is at idle or moving at low speeds.

The fan size is 366 mm (14.4 in) in diameter with 5 blades to aid the airflow through the radiator and the condenser. A non-A/C model is 300 mm (11.8 in). An electric motor attached to the radiator support drives the fan.

A/C OFF or Non-A/C Model

1. The cooling fans are actuated by the engine control module (ECM) using a low-speed cooling fan relay and a high-speed cooling fan relay. On A/C-equipped vehicles, a series/parallel cooling fan relay is also used.
2. The ECM will turn the cooling fans ON at low speed when the coolant temperature reaches 93°C (199°F) and high speed at 97°C (207°F).
3. The ECM will change the cooling fans from high speed to low speed at 94°C (201°F) and turn the cooling fans OFF at 90°C (194°F).

A/C ON

1. The ECM will turn the cooling fans ON at low speed when the A/C system is ON. The ECM will change to high speed when the coolant temperature reaches 97°C (207°F) or high-side A/C pressure reaches 1 882 kPa (273 psi).
2. The cooling fans will return to low speed when the coolant temperature reaches 94°C (201°F) or high-side A/C pressure reaches 1 448 kPa (210 psi).

Engine Coolant Temperature (ECT) Sensor

The engine coolant temperature (ECT) sensor uses a thermistor to control the signal voltage to the engine control module (ECM) and controls the instrument panel temperature indicator. The ECT sensor is located on the cylinder head. Refer to the appropriate engine controls section for diagnosis and replacement of the engine coolant temperature (ECT) sensor.

Engine Block Heater

The vehicle is designed to accept an engine block heater. The engine block heater helps to warm the engine for improved cold weather starting. It can also help reduce fuel consumption when a cold engine is warming up.

The engine block heater utilizes an existing expansion plug for installation and is located in the engine block in an existing freeze plug port.

Contact your General Motors dealer for further information or installation.

Special Tools

Special Tools Illustration Tool Number/ Description KM-471 Adapter

Scheme 6

See also:
• Scan Tool Does Not Power Up
• Diagnostic Trouble Code (DTC) List
• Testing for Intermittent Conditions and Poor Connections
• Circuit Testing
• Wiring Repairs
• Repairing Connector Terminals
• Relay Replacement (Within an Electrical Center)
• Electric Coolant Fan Caution
• DTC P0532 or P0533
• Engine Control Module (ECM) Replacement
• Connector Repairs
• Battery Disconnect Caution
• Fastener Notice
• Radiator Cap Removal Caution
• Symptoms - Engine Cooling
• Cooling System Connector End Views
• Engine Overheating
• Loss of Coolant
• Thermostat Diagnosis
• Coolant Heater Inoperative
• Engine Fails To Reach Normal Operating Temperature
• Diagnostic Starting Point - Engine Cooling
• Coolant Heater Cord Replacement
• Special Tools
• Draining and Filling Cooling System