Mechanics

COOLING FAN

2001 Pontiac Sunfire

Engine Cooling problem
2001 Pontiac Sunfire 4 cyl Two Wheel Drive Automatic

how do I solve the problem when my cooling fan is not working?
Avatar
Natureman777
August 30, 2008.



Hi natureman777,

2.2L & 2.4L CAVALIER & SUNFIRE
Description
Cooling fan is controlled by Powertrain Control Module (PCM) through cooling fan relay based on inputs from engine coolant temperature sensor, intake air temperature sensor, A/C control switch, A/C refrigerant pressure sensor and Vehicle Speed Sensor (VSS).
PCM controls cooling fan motor by grounding cooling fan relay control circuit which closes fan relay contacts. Cooling fan relay is commanded on when:  Engine coolant temperature reaches 223 °F (106 °C) or greater.
 A/C refrigerant pressure exceeds 190 psi.  During extended idle conditions less than 5 MPH.  After vehicle is shut off if engine coolant temperature at key-off is greater than 284 °F (140 °C) and system voltage is more than 12 volts. Fan will stay on for approximately 3 minutes. Diagnostic System Check
1. Install scan tool. If scan tool powers up, go to next step. If scan tool does not power up, see SCAN TOOL DOES NOT POWER UP in appropriate BODY CONTROL MODULES article.
2. Turn ignition on, engine off. Try to establish scan tool communication with Powertrain Control Module (PCM). If communication with PCM is established, go to next step. If communication with PCM is not established, see SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE in appropriate BODY CONTROL MODULES article.
3. Select display DTC function for PCM. Record all displayed DTCs and status of displayed DTCs. If DTCs are displayed, go to next step. If no DTCs are displayed, see COOLING FAN INOPERATIVE or COOLING FAN ALWAYS ON.
4. If scan tool does not display DTCs beginning with " U", see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. If scan tool displays DTCs beginning with " U", see SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE in appropriate BODY CONTROL MODULES article.
Cooling Fan Inoperative
1. If diagnostic system check has not been performed, see DIAGNOSTIC SYSTEM CHECK. If diagnostic system check has been performed, go to next step.
2. Install a scan tool. Turn ignition on, engine off. Using scan tool, command cooling fan on and off. If engine cooling fan turns on and off with each command, problem is intermittent. If engine cooling fan does not turn on and off with each command, go to next step.
3. Turn ignition off. Remove cooling fan relay. Turn ignition on, engine off. Probe battery voltage circuit (terminal No. 30) of cooling fan relay switch side with test light connected to ground. If test light illuminates, go to next step. If test light does not illuminate, go to step 7.
4. Connect fused jumper (20-amp) between battery voltage circuit (terminal No. 30) of cooling fan relay and cooling fan motor supply voltage circuit (terminal No. 87) of cooling fan relay. If cooling fan operates, go to step 10. If cooling fan does not operate, go to next step.
5. Turn ignition off. Disconnect cooling fan connector. Turn ignition on, engine off. Probe cooling fan motor supply voltage circuit (Light Blue wire) at harness connector with test light connected to ground. If test light illuminates, go to next step. If test light does not illuminate, go to step 8.
6. Probe harness connector of cooling fan motor with test light between cooling fan motor connector terminals. If test light illuminates, go to step 11. If test light does not illuminate, go to step 9.
7. Repair battery positive circuit (Red wire) of cooling fan relay. After repairs, go to step 14.
8. Repair supply voltage circuit (Light Blue wire) of cooling fan motor. After repairs, go to step 14.
9. Repair ground circuit (Black/White wire) of cooling fan motor. After repairs, go to step 14.
10. Check cooling fan relay connector for poor connections. If problem was found, repair as necessary. After repairs, go to step 14. If problem was not found, go to step 12.
11. Check cooling fan motor connector for poor connections. If problem was found, repair as necessary. After repairs, go to step 14. If problem was not found, go to step 13.
12. Replace cooling fan relay. After repairs, go to step 14.
13. Replace cooling fan motor. After repairs, go to next step.
14. Operate system to verify repair.
Cooling Fan Always On
1. If diagnostic system check has not been performed, see DIAGNOSTIC SYSTEM CHECK. If diagnostic system check has been performed, go to next step.
2. Turn ignition on, engine off. If engine cooling fan runs all the time, go to next step. If engine cooling fan does not run all the time, problem is intermittent.
3. Remove cooling fan relay. If cooling fan turned off, go to step 5. If cooling fan did not turn off, go to next step.
4. Repair short to power in cooling fan motor supply voltage circuit (Light Blue wire). After repairs, go to step 7.
5. Check cooling fan relay for poor connections. If problem was found, repair as necessary. After repairs, go to step 7. If problem was not found, go to next step.
6. Replace cooling fan relay. After repairs, go to next step.
7. Operate system to verify repair. Diagnostic Aids Whenever owner complains of an overheating problem, determine if complaint was due to an actual boilover, or TEMP light or gauge indicated overheating. Whenever gauge or light indicates overheating, but no boilover is detected, gauge or light circuit should be checked. Gauge accuracy can also be checked by comparing engine coolant temperature sensor reading with gauge reading. If engine is actually overheating, and gauge indicates overheating, but cooling fan is not coming on, ECT sensor has probably shifted out of calibration and should be replaced. Whenever engine is overheating and cooling fan is on, cooling system should be checked.

9/1/2008

KHLow2008
Aug 31, 2008.