Century V6-231 3.8L (1985)
Radiator Cooling Fan Motor: Description and Operation
On models equipped with electric engine cooling fans, the battery ground cable should be disconnected whenever underhood service is performed.
1985 BUICK CENTURY & OLDSMOBILE CUTLASS CIERA
System Description
The cooling fan is controlled by a cooling fan relay whose coil is grounded by the cooling fan switch when coolant temperature exceeds 228 degrees
F. The cooling fan relay is energized and its contacts close to supply battery voltage to cooling fan. The cooling fan delay relay operates cooling fan for
short time after engine is turned off. A solid state timer removes ground from cooling fan delay relay coil to switch off cooling fan.
V6-231 VIN 3
Three types of cooling fans are used with V6-231 VIN 3 engines:
a.
Single speed.
b.
Two speed (internal resistor).
c.
Heavy Duty Two Speed (external resistor).
On vehicles with single speed cooling fans, cooling fan relay coil is grounded through cooling fan switch. At coolant temperatures exceeding 228
degrees F, switch contacts close and ground relay coil causing relay contacts to close, thus applying battery voltage to cooling fan. On vehicles with
two speed cooling fans, low speed cooling fan relay coil is grounded through low speed contacts of A/C high pressure switch (with A/C on) or through
ground provided by ECM. On vehicles with Heavy Duty Two Speed cooling fan less A/C, ground is only provided by ECM with vehicle speed below 35
mph. With low speed cooling fan relay coil grounded, relay contacts close, applying battery voltage through cooling fan resistor to heavy duty fan or
directly to two speed fan. The resistor which is external with heavy duty cooling fan; internal with two speed fan, drops part of voltage so fan runs at low
speed. During high speed operation, high speed cooling fan relay coil is grounded through high speed contacts of A/C high pressure switch (with A/C
on) or cooling fan switch. With high speed cooling fan relay coil grounded, relay contacts close. Battery voltage is applied directly to cooling fan
causing it to run at high speed.
System Check
BUICK CENTURY
Less A/C
1.
Run engine at fast idle for several minutes.
2.
Cooling fan should turn on before coolant temperature indicator in instrument panel comes on.
With A/C
1.
With engine at normal operating temperature, and running at curb idle, set A/C mode selector to NORM position. Cooling fan should turn on.
2.
Set A/C mode selector to OFF. Run engine at fast idle for several minutes. Cooling fan should come on before coolant temperature indicator on
instrument panel comes on.
Troubleshooting
BUICK CENTURY
If cooling fan relay has failed, replace it and check cooling fan switch for intermittent operation as flows:
1.
Warm up engine until cooling fan turns on.
2.
Disconnect connector from cooling fan switch.
3.
Connect self-powered test lamp to switch and to ground. Test lamp should light steadily.
4.
If test lamp flickers, replace cooling fan switch.
5.
Perform test on both high and low speed switches, if equipped.
Cooling Fan Does Not Operate
1.
Check applicable A/C or heater fuse. On V6-231 VIN 3, check ECM/ERLS fuse.
2.
On all models, check for loose connections on fan and relays.
3.
If OK, connect fused jumper wire from positive battery terminal to cooling fan black/red and/or pink/black wires.
4.
If fan does not run, check that black wire is grounded and that fan mounting bolts are clean and tight. If fan is properly grounded and does not run,
replace cooling fan.
5.
If cooling fan runs in step 3, problem is in control switches or wiring:
a. On vehicles with 4-151 VIN R, V6-183 VIN E with A/C, V6-231 VIN 3, perform ECM diagnosis.
b. On vehicles with V6-183 VIN E less A/C, or V6-262 Diesel VIN T, refer to ``System Diagnosis.''
System Diagnosis
BUICK CENTURY W/V6-231 VIN E LESS A/C
SINGLE SPEED FAN
Fan Runs When Jumped; Does Not Run In Normal Use
1.
Disconnect connectors from cooling fan relay. With ignition switch in RUN position, check for battery voltage at terminal A (brown wire), and at
terminal B (red wire).
2.
If battery voltage is not available at a terminal, check circuit that supplies terminal. If voltages are correct, proceed to step 3.
3.
Connect connector to cooling fan relay.