APPLICATION
| Application | Engine |
|---|---|
| Lumina APV, Silhouette & Trans Sport | 3.1L |
| "C" & "K" Series, "G" Series & "R" & "V" Series with A/C | 7.4L |
ELECTRIC COOLING FAN APPLICATION
DESCRIPTION
On Lumina APV, Silhouette and Trans Sport, electric cooling fan provides cooling for radiator and A/C condenser. On "C", "G", "K", "R" and "V" Series, electric cooling fan is an auxiliary unit that provides cooling for A/C condenser.
LUMINA APV, SILHOUETTE & TRANS SPORT
ECM completes path to ground for cooling fan relay to activate cooling fan motor. Cooling fan relay is the center of 3 relays behind right headlight. A fusible link protects the circuit. When the engine cools, ECM opens relay and fan stops. If coolant sensor fails, the ECM commands constant fan operation.
A/C-equipped vehicles have a separate signal line to ECM for fan control. When A/C control switch is on and A/C system low pressure switch is closed, the ECM receives a signal on this line to turn on cooling fan. The compressor clutch does not have to engage for ECM to turn fan on.
On some models, ECM may turn on the fan relay and run fan motor for up to 7 minutes when engine is off. This occurs if hot conditions were present while engine was running. Hot condition determination is based on running time, coolant temperature and Manifold Air Temperature (MAT) signal to ECM.
"C", "G" "K", R" & "V" SERIES
Coolant temperature switch closes when predetermined temperature is reached. Relay contacts then close, completing circuit to fan motor.
Switch is located on right cylinder head, above center of exhaust manifold. On "G" Series, relay is located in engine compartment on center of firewall. On "C", "K", "R" and "V" Series, relay is mounted to left inner fender, near engine compartment firewall.
LUMINA APV, SILHOUETTE & TRANS SPORT WITH REAR HEATER
Turn off blower switch while filling cooling system. This ensures maximum coolant flow to rear heater system.
TROUBLE SHOOTING & TESTING
Note. Some TROUBLE SHOOTING & TESTING consists of General Motors Computerized Engine Control system test charts. Only those charts required to test electric cooling fans are included. For complete information on General Motors Computerized Engine Control systems, see ENGINE PERFORMANCE.
Note. For cooling fan circuit wiring diagram (Scheme 5)in WIRING DIAGRAMS.
Cooling Fan System Diagnosis (Lumina APV, Silhouette & Trans Sport - 1 Of 2). Scheme 1
The ECM controls cooling fan based on inputs from coolant temperature sensor (located in front of distributor on left side of engine), A/C fan control switch and vehicle speed. The ECM grounds the circuit to the cooling fan control relay. This energizes fan control relay for fan operation. Wiring circuit to fan control relay is grounded when coolant temperature exceeds 223°F (106°F) or when A/C is operating and A/C fan control switch opens with high A/C pressure of approximately 200 psi (14.1 kg/cm 2 ).
Note. Test numbers refer to test numbers on diagnostic charts.
- With ALDL diagnostic terminal grounded, cooling fan driver closes and energizes fan control relay.
- If A/C fan control switch or circuit is open, cooling fan operates whenever A/C is operating.
- With A/C clutch energized, A/C fan control switch should open when A/C high pressure exceeds 200 psi (14.1 kg/cm 2 ). This signal indicates that ECM should energize fan control relay.
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 cooling fan is not operating, and Scan tester indicates normal readings, coolant temperature sensor is out of calibration and should be replaced. If engine is overheating and cooling fan is on, check cooling system.
Cooling Fan System Diagnosis (Lumina APV, Silhouette & Trans Sport - 2 Of 2). Scheme 2
Note. Test numbers refer to test numbers on diagnostic charts.
Scheme 3
Scheme 4
- Battery voltage should be available at both terminals "A" and "D" when ignition switch is on.
- This checks the ECM's ability to ground circuit No. 335. The SERVICE ENGINE SOON light should be flashing at this point. If SERVICE ENGINE SOON light is not flashing, refer to ENGINE PERFORMANCE.
- If cooling fan does not turn on at this point, circuit No. 150 or 702 is open or the cooling fan motor is defective. (Scheme 3): Cooling Fan Circuit Diagram & System Diagnosis ("C" & "K" Series with 7.4L)
- Turn ignition on. Disconnect cooling fan relay connector. Check for battery voltage at Pink/Black wire terminal of relay connector. If no voltage is present, check 20A GAGES fuse and Pink/Black wire.
- If battery voltage is present, check for battery voltage at Red wire terminal of relay connector. If no voltage is present, check Gray fuse link. If battery voltage is present, check continuity between Pink/Black and Dark Green wire terminals of relay.
- If there is no continuity, replace relay. If there is continuity, ensure coolant temperature is more than 225°F (107 °C). Check continuity between ground and Dark Green wire terminal of relay connector.
- If there is continuity, go to next step. If there is no continuity, check continuity of Dark Green wire between relay and coolant temperature switch. If there is no continuity, repair Dark Green wire between relay and switch. If there is continuity, replace switch.
- Check continuity between Black/Red wire terminal of relay connector and Black wire terminal of cooling fan connector. If there is no continuity, repair circuit between relay and fan. If there is continuity, check continuity of fan ground wire. If there is no continuity, repair ground wire.
- If there is continuity, apply battery voltage to fan. If fan does not operate, replace fan. (Scheme 4): Cooling Fan Circuit Diagram & System Diagnosis ("G","R" & "V" Series with 7.4L)
