Pontiac Fiero 1988 Service Manual page 1001

COOLANT
FAN
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V6 ¥1119
(Continued from previous page)
D: COOLANT FAN AND ENGINE
BLOWER
RUN CONTINUOUSLY
1. With the Ignition Switch in RUN, discon-
nect the Coolant Temperature Switch con-
nector.
• If the Coolant Fan runs, go to step 2.
• If the Coolant Fan does not run, replace
the Coolant Temperature Switch.
2. Disconnect the A/C High Pressure Cut-Out
Switch connector.
• If the Coolant Fan runs, go to step 3.
• If the Coolant Fan does not run, replace
the A/C High Pressure Cut-Out Switch.
3. Disconnect the A/C Control Head connector.
• If the Coolant Fan runs, check DK
GRN/WHT (335) wire for short to
ground.
• If the Coolant Fan does not run, replace
the A/C Control Head.
L4 VIN RAND ¥ 6 VIN 9
CIRCUIT OPERATION
L 4 V I N R
The Coolant Fan is turned on and off by the
ECM based on inputs from the Coolant Tem-
perature Sensor, Vehicle Speed Sensor and the
A/C System. Battery Voltage is applied at all
times to terminal A of the Coolant Fan Relay.
The ECM energizes the Coolant Fan Relay by
grounding circuit 335. The Relay energizes
and battery voltage is applied to the Coolant
Fan. See Section 6E for specific conditions of
the Coolant Fan operation.
The A/C Control Head also energizes the
Coolant Fan Relay by grounding circuit 335
whenever the A/C Function Selector is in MAX,
NORM or B/L.
Vi
VIN
3
The Coolant Fan is operated by the Coolant
Fan Relay. Battery voltage is applied at all
times through Fusible Link A to terminal A of
the Coolant Fan Relay. With the Ignition
Swith in RUN, voltage is applied through the
FAN E Fuse to terminal D of the Relay coil.
When the coolant temperature exceeds 113°C
(235°F), the Coolant Temperature Switch closes.
By grounding circuit 335, the Relay coil is ener-
gized and battery voltage is applied to the
Coolant Fan.
If equipped with Air Conditioning, the A/C
High Pressure Cut-Out Switch and A/C Control
Head also energize the Coolant Fan Relay by
grounding circuit 335 whenever the A/C High
Pressure Cut-Out Switch closes above 280
PSI (1931 kPa) and the A/C Function Selector
is in MAX, NORM or B/L.