Bonneville V6-3800 3.8L Supercharged (1992)
Radiator Cooling Fan Motor: Description and Operation
Two Coolant Fans, wired in parallel, operate whenever cooling is required.
The Powertrain Control Module (PCM) has two Coolant Fan terminals: one for high speed and one for low speed. When the PCM's low speed control
closes at connector C3, terminal C4, it grounds the Low Speed Coolant Fan Relay coil. When the Ignition Switch is in the RUN position and the relay
contacts close, voltage is supplied to the Coolant Fans. The Coolant Fan Resistors drop the voltage to the LH Coolant Fan, causing it to run in low speed.
The RH Coolant Fan also runs, but at high speed because the Coolant Fan Resistors are bypassed. The PCM's low speed output is turned on when
coolant temperature reaches 100°C (212°F).
High speed operation is similar to that of low speed. When coolant temperature reaches 108°C (226°F), the PCM's high speed control closes at connector
C3, terminal C3, grounding the High Speed Coolant Relay coil. The relay contacts close and both fans run at high speed since the PCM's low speed
control remains closed. When A/C head pressure reaches 1445 kPa (210 psi), the A/C Pressure Fan Switch closes, grounding the PCM input connector
C1, terminal D9. This also causes the PCM high speed control to close, and both Coolant Fans run at high speed.
