Pontiac Fiero 1988 Service Manual page 1042

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CIRCUIT OPERATION
The Blower Motor delivers air to the interior of
the vehicle. Its speed is controlled by the Blower
Switch and the Blower Resistors. When the
Ignition Switch is in RUN, battery voltage is
applied to the Blower Switch. With the Blower
Switch in LO, voltage is applied across both
Blower Resistors and the Blower Motor. The
Blower Motor runs at its slowest speed. With the
Blower Switch in MED, one of the Blower
Resistors is bypassed and the Blower Motor runs
faster. When the Blower Switch is set to HI, the
High Speed Blower Relay is energized. The relay
contacts close and battery voltage is applied
directly to the Blower Motor. The Blower Motor
runs at its fastest speed.
D: HIGH SPEED BLOWER RELAY TEST
(TABLE 2)
Connect: FUSED JUMPER
At: HIGH SPEED BLOWER RELAY
CONNECTOR (Disconnected)
Jumper
Between
Correct Result For Diagnosis
D (RED) & B
(PPL)
Blower Motor
runs
Seel
• If the result is correct, replace the High
Speed Blower Relay.
1. Check PPL (65) wire for an open (see
schematic).
A (ORN) &
Ground
Battery See 2
A (ORN) & C
(BLK)
Battery See 3
• If all voltages are correct, go to Table 2.
1. Check RED (2) wire and Fusible Link A for
an open (see schematic).
2. Check ORN (52) wire for an open. Perform
Test A: Blower Switch Test if ORN (52)
wire is OK.
3. Check BLK (150) wire for an open (see
schematic).