Firenza L4-121 2.0L VIN K TBI (1987)
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---87 BUICK SKYHAWK, OLDSMOBILE FIRENZA & PONTIAC SUNBIRD
SYSTEM DESCRIPTION
The cooling fan cools both engine coolant and A/C system refrigerant.
4-121 VIN P
Cooling fan relay is activated by ECM when engine coolant sensed by coolant temperature sensor is above 238 degrees F and vehicle speed is below
35 mph. ECM also activates cooling fan relay when A/C mode selector sends voltage to ECM. Cooling fan will also run if cooling fan switch and A/C
high pressure switch are closed, such as when A/C mode selector is in DEF position and ambient temperature is above 32 degrees F and A/C system is
properly charged.
SYSTEM CHECK
With A/C
1.
When engine at normal operating temperature and idle speed, set A/C mode selector to NORM. Cooling fan should turn on.
2.
Set mode selector off. Allow engine to run at fast idle for several minutes. Cooling fan should turn on before coolant temperature indicator in
instrument panel comes on or before coolant temperature gauge reaches H.
3.
On models with 4-110 Turbo VIN J engine, turn engine off when at normal operating temperature. Cooling fan should run for 5 minutes.
Less A/C
1.
Run engine at fast idle for several minutes. Coolant fan should turn on before coolant temperature indicator in instrument panel comes on or before
coolant temperature gauge reaches H.
2.
On models with 4-110 Turbo VIN J engine, turn engine off when at normal operating temperature. Cooling fan should run for 5 minutes.
TROUBLESHOOTING
1.
If cooling fan only comes on with A/C compressor and not for a hot engine, install new cooling fan switch.
2.
Connect a fused jumper wire from positive terminal of battery to terminal B (black/red) on all Buick Skyhawk engines and on Oldsmobile Firenza
and Pontiac Sunbird with 4-121 VIN P engine; to terminal B (red/white) on Pontiac Sunbird with 4-110 Turbo VIN J engine; to terminal A
(red/white) on Oldsmobile Firenza and Pontiac Sunbird with 4-110 VIN O engine.
a. If fan runs, ECM diagnosis must be performed since circuit is controlled by ECM.
b. If fan does not run, check continuity to ground at terminal B on Oldsmobile Firenza and Pontiac Sunbird with 4-110 VIN O engine; terminal
A on models exc. Oldsmobile Firenza and Pontiac Sunbird with 4-110 VIN O engine.
3.
If a cooling fan relay has failed, test cooling fan switch for intermittent operation as follows:
a. Warm up engine until cooling fan comes on.
b. Remove connector from cooling fan switch.
c. Connect self-powered test lamp to switch and to ground. Test lamp should light steadily. If test lamp flickers, install new cooling fan switch.
d. Test both high speed and low speed switches if vehicle is so equipped.
COOLING FAN, REPLACE
1.
Disconnect battery ground cable.
2.
Disconnect wiring from fan motor and frame.
3.
Remove fan assembly from radiator support.
4.
Reverse procedure to install.
