Ninety-Eight V6-3800 3.8L (1989)
Radiator Cooling Fan Motor: Description and Operation
A two speed coolant fan is turned on and off by the low and high speed coolant fan relays.
For low speed operation, the low speed relay coil is grounded through the ECM. The ECM grounds the coil when engine coolant is above 208°F.
With low speed relay coil grounded, its contacts close. Voltage is applied through the coolant fan resistor to the coolant fan. The resistor reduces
voltage supplied to the fan so the fan runs at low speed.
For high speed operation, the high speed relay coil is grounded through the high speed contacts in the A/C coolant fan pressure switch or by the ECM.
The A/C coolant fan pressure switch high speed contacts close at a refrigerant pressure above 275 psi.
With the high speed coil grounded, its contacts close. Battery voltage is applied to the coolant fan. The fan runs at high speed.
The auxiliary coolant fan, if equipped, operates whenever the coolant fan runs at high speed. The A/C coolant fan pressure switch and ECM also
control the auxiliary coolant fan relay, if equipped, which supplies battery voltage to the auxiliary coolant fan when energized.