Engine Cooling Fan Chevrolet Beretta I

DESCRIPTION

All FWD and some RWD vehicles use an electric cooling fan. The electric cooling fan is used for engine and A/C condenser cooling and operates when A/C is on and if engine overheats.

OPERATION

All electric cooling fans operate when engine coolant temperature exceeds a certain value. The ECM completes ground path for the cooling fan relay. Relay contacts then close and complete circuit between fusible link and fan motor. When the engine cools, the switch opens and fan stops. If coolant sensor fails, the ECM will command constant fan operation.

A/C-equipped vehicles have a separate signal line to the ECM for fan control. When A/C control switch is on, and A/C system low pressure switch is closed, ECM receives a signal on this line and turns cooling fan on. The compressor clutch does not have to engage for ECM to turn fan on.

On some models, when engine is off, ECM may turn on the fan relay and run fan for up to 7 minutes. This occurs if hot conditions were present while engine was running. Hot conditions are based on Manifold Absolute Temperature (MAT) signal to ECM, coolant temperature and time from start.

TROUBLE SHOOTING

See trouble shooting charts for cooling fan diagnosis.

COOLING FAN CHART INDEX

CHART C-12: COOLING FAN (2.2L VIN G)

Battery voltage is supplied on circuit No. 2 to operate cooling fan motor. Ignition voltage is supplied on circuit No. 39 to energize cooling fan relay. The cooling fan is energized when ECM grounds circuit No. 335. With engine running, ECM will energize cooling fan when

1. A/C is on.
2. Coolant temperature is greater than 230°F (110°C).
3. Code 14 or 15 is set.

Diagnostic Aids

If an overheating condition is suspected, verify if this is due to actual boilover. If gauge or light indicates an overheat condition, and no boilover is in evidence, inspect the gauge/light circuit for malfunction.

If vehicle is overheating and the gauge or light indicates the same, but the cooling fan is not coming on, check coolant sensor temperature using a Scan tester. Sensor may have shifted calibration. If engine is overheating and cooling fan is on, check cooling system.

Scheme 1

Scheme 2

CHART C-10: A/C CLUTCH CONTROL (2.2L VIN G)

When A/C is selected, ignition voltage is supplied to the compressor low pressure switch. If A/C system charge is sufficient, low pressure cut-off switch will close and complete a circuit to the high pressure cut-off switch and circuits No. 67 and 366. Voltage on circuit No. 366 to the ECM is displayed by "Scan" tester as A/C request on (voltage present). ECM will ground circuit No. 459 of A/C clutch control relay. Relay will close and current will flow from circuit No. 366 to circuit No. 59, engaging A/C compressor clutch. A "Scan" tool will show the grounding of circuit No. 459 as A/C clutch on. When ECM sees voltage on circuit No. 366, cooling fan will be turned on.

The low pressure switch will be closed between 40-47 psi (2.8-3.3 kg/cm 2 ) allowing A/C clutch operation. With less than 37 psi (2.6 kg/cm 2 ), the low pressure switch will open, stopping A/C clutch operation.

At approximately 430 psi (30 kg/cm 2 ) the high pressure switch will open, disengaging A/C clutch operation. This will prevent system damage.

Scheme 3

Scheme 4

CHART C-12: COOLING FAN (2.3L VIN A)

The engine cooling fan is controlled by the ECM through a fan relay. The ECM controls fan relay with inputs from coolant temperature sensor, manifold air temperature sensor, A/C control switch, A/C pressure sensor and Vehicle Speed Sensor (VSS). ECM controls the cooling fan by grounding circuit No. 335, which energizes fan relay. The fan relay will be energized when

1. A/C clutch is requested.
2. Coolant temperature is 217-222°F (103-106°C).
3. Vehicle speed is less than 35 MPH.

Fan relay will be commanded on regardless of vehicle speed when

1. A/C pressure is high.
2. Code 14 or 15 is set.
3. Coolant temperature is 239-244°F (115-118°C).

Note. Test numbers refer to test numbers on diagnostic charts.

1. With field service mode activated, cooling fan control driver should close, energizing fan control relay.
2. This checks to see if fault is in wiring or fan connection.

If an overheating condition is suspected, verify if this is due to actual boil-over. If gauge or light indicates an overheat condition, and no boilover is in evidence, inspect the gauge/light circuit for malfunction.

If vehicle is overheating and the gauge or light indicates the same, but the cooling fan is not coming on, check coolant sensor temperature using a "Scan" tester. Sensor may have shifted calibration. If engine is overheating and cooling fan is on, check cooling system.

Scheme 5

Scheme 6

CHART C-12, COOLING FAN (3.1L VIN T)

Electric cooling fan is controlled by ECM based on inputs from coolant temperature sensor, A/C fan control switch and vehicle speed. ECM controls cooling fan by grounding circuit No. 335, energizing fan control relay. Battery voltage is then supplied to fan motor.

ECM grounds circuit No. 335 when coolant temperature is more than 228°F (109°C) or when A/C has been requested and fan control switch opens with high A/C pressure of 200 psi (14 kg/cm 2 ). Once ECM turns relay on, it will keep relay on for a minimum of 30 seconds or until vehicle speed exceeds 70 MPH. Cooling fan will also run constantly when Code 14 or 15 is present or if ECM in back-up mode.

Note. Test numbers refer to test numbers on diagnostic charts.

1. With diagnostic terminal grounded, the cooling fan control driver will close, energizing fan control relay.
2. If A/C fan control switch or circuit is open, cooling fan will run whenever A/C is requested.
3. With A/C clutch engaged, the A/C fan control switch should open when A/C high pressure exceeds 200 psi (14.1 kg/cm 2 ). This signal should cause ECM to energize fan control relay.
4. Disconnecting A/C pressure sensor will set Code 66. After finishing this step, ensure codes are cleared.

If an overheating condition is suspected, verify if this is due to actual boil-over. If gauge or light indicates an overheat condition, and no boilover is in evidence, inspect the gauge/light circuit for malfunction.

If vehicle is overheating and the gauge or light indicates the same, but cooling fan is not coming on, check coolant sensor temperature using a "Scan" tester. Sensor may have shifted calibration and should be replaced. If engine is overheating and cooling fan is on, check cooling system.

Scheme 7

Scheme 8

Note. Test numbers refer to test numbers on diagnostic charts.

Scheme 9

1. Battery voltage should be present at terminals A and D when ignition is on.
2. This checks ECM's ability to ground circuit No. 335. The SERVICE ENGINE SOON light should be flashing at this time. If SERVICE ENGINE SOON light is not flashing, refer to ENGINE PERFORMANCE section.
3. If cooling fan does not run at this point, circuit No. 150 or 702 is open or cooling fan motor is faulty.

CHART C-10, A/C CLUTCH CONTROL (3.1L VIN T)

The A/C clutch control relay is energized when ECM provides ground path through circuit No. 459 when A/C is requested. A/C clutch is delayed 3/10 of a second after A/C is requested, allowing the Idle Air Control (IAC) to adjust engine RPM for the additional load.

ECM will temporarily disengage the A/C clutch relay for calibrated times for one of the following conditions

1. Hot engine restarts.
2. Wide open throttle (TPS over 90%).
3. Power steering pressure high (open PSPS switch).
4. Engine speed greater than 6000 RPM.
5. During IAC retest.

A/C clutch will remain disengaged when Code 66 is set, if pressure is out of range or there is no A/C request signal due to an open A/C select switch or circuit.

Note. Test numbers refer to test numbers on diagnostic charts.

Scheme 10

Scheme 11

1. ECM will only energize A/C relay when engine is running. This test will determine if relay or circuit No. 459 is faulty.
2. Test determines if signal is reaching the ECM through circuit No. 66 from the A/C control panel. Signal should only be present when A/C or defrost mode has been selected. NOTE: Test numbers refer to test numbers on diagnostic charts.
3. Determines if pressure transducer is out of range causing A/C compressor clutch to be disengaged.
4. With engine not running and field service mode activated, ECM should be grounding circuit No. 459, which should activate test light.

If complaint is insufficient cooling, problem may be caused by an inoperative cooling fan. See CHART C-12 for cooling fan diagnosis. If cooling fan operates properly, check A/C system. A/C pressure outside the range of 43-428 psi (3-30 kg/cm 2 ) will cause ECM to disable compressor. Observe "Scan" tester A/C pressure for 2 minutes with engine at idle and A/C on. "Scan" tester A/C pressure should be within 20 psi (1.4 kg/cm 2 ) of actual reading. If pressure is out of range, refer to A/C-HEATER SYSTEM - MANUAL article in this section or check for problem using Code 66 chart or replace sensor. Refer to ENGINE PERFORMANCE section.

Scheme 12

CHART C-1E, P/S PRESSURE SWITCH (3.1L VIN T)

Power Steering Pressure Switch (PSPS) is normally open to ground. Circuit No. 495 should have near battery voltage. Power steering pressure increases as steering wheel is turned. PSPS will close (less than one volt on circuit No. 495), disengaging A/C compressor clutch and increasing idle air rate.

A PSPS that will not close or an open in circuits No. 495 or 450 may cause engine to stall when power steering load is high. A PSPS that will not open or a short to ground on circuit No. 495, may affect engine idle and will not allow A/C compressor clutch operation.

Note. Test numbers refer to test numbers on diagnostic charts.

Scheme 13

1. Different makes of "Scan" testers may display the state of PSPS switch in different ways. Refer to operation manual for your particular tester.
2. This step checks if circuit No. 495 is shorted to ground.
3. This step simulates a closed PSPS switch.

See also:
• A/C-HEATER SYSTEM - MANUAL