Cutlass Ciera Cruiser L4-151 2.5L (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.
4-151 VIN R
The cooling fan is controlled by the following:
1.
Coolant temperature fan switch.
2.
ECM and A/C mode selector switch.
3.
ECM and A/C high pressure switch.
These switch combinations complete circuit to ground through cooling fan relay coil. With coil energized and relay contacts closed, battery voltage is
applied to cooling fan. On vehicles equipped with A/C, cooling fan also runs when compressor is on. With A/C mode selector is in MAX, NORM, or
BI-LEVEL position, a path to ground exists through mode selector switch and ECM. A suppression resistor is connected across cooling fan relay coil
to absorb voltage spikes. An A/C high pressure switch is included in A/C relay grounding circuit to ensure grounding of cooling fan relay coil and
cooling fan operation when mode selector is in DEF position and ambient temperature is above 32 degrees F.
OLDSMOBILE CUTLASS CIERA
4-151 VIN R Less A/C
1.
Run engine at fast idle for several minutes. Cooling fan should turn on before coolant temperature indicator comes on.
4-151 VIN R With A/C
1.
With engine at normal operating temperature and running at curb idle, move A/C selector switch to NORM position. Cooling fan should go on.
2.
Move A/C selector switch to OFF position. Allow engine to run at fast idle for several minutes. Cooling fan should turn on before coolant
temperature indicator goes on.
OLDSMOBILE CUTLASS CIERA W/4-151 VIN R
1.
If cooling fan comes on only with A/C compressor and not for hot engine, install new cooling fan switch.
2.
If cooling fan does not come on with A/C compressor, check for continuity to ground at terminal A (dark green/yellow wire) of A/C selector
switch. If ground is good, check for continuity between terminal B of A/C selector switch and terminal B of coolant fan relay (dark green/white
wire) with relay disconnected. If good, replace A/C selector switch.
OLDSMOBILE CUTLASS CIERA
4-151 VIN R
Cooling Fan Does Not Run
1.
Check that cooling fan case ground is clean and tight.
2.
Check F-P fuse.
3.
Turn ignition switch to RUN without starting engine. Disconnect cooling fan switch connector (dark green/white wire). Connect jumper wire from
dark green/white wire to ground and leave connected for duration of test.
4.
If fan runs, replace cooling fan switch.
5.
If fan does not run in step 3, connect test lamp to ground and check for voltage at terminal C (brown/white wire) of coolant fan relay.
6.
If test lamp does not light, repair open in brown/white or brown wire between relay and fuse block.
7.
If test lamp lights in step 5, check for voltage at terminal D (red wire).
8.
If test lamp does not light, check and, if necessary, repair red wire between relay and fusible link C. Check and, if necessary, repair fusible link C.
9.
If test lamp lights in step 7, check for voltage at terminal B (dark green/white wire) of relay.
10.
If test lamp lights, repair open in dark green/white wire between relay and cooling fan switch.
11.
If test lamp does not light, check for voltage at terminal A (black/red wire) of relay.
12.
If test lamp does not light, replace cooling fan relay.
13.
If test lamp lights in step 11, check for voltage at cooling fan connector (black/red wire).
14.
If test lamp does not light, repair open in black/red wire between relay and cooling fan.
15.
If test lamp lights in step 13, repair or replace cooling fan.
