Radiator Cooling Fan Temperature Sensor / Switch: Description and Operation

These models use two cooling fans, two thermo sensors and four relays to control the cooling fan operation.
With A/C off and engine coolant temperature below 194°F, the cooling fans will not operate. When coolant temperature exceeds 194°F, thermo sensor No. 1 closes and No. 1 cooling fan operates at low speed (1400 RPM). When coolant temperature reaches 212°F, thermo sensor No. 2 closes and cooling fan No. 1 operates at high speed (2000 RPM) while cooling fan No. 2 operates at its one speed (1700 RPM).
With A/C control on, compressor off, thermo sensor No. 1 open or closed and coolant temperature below 212°F, No. 1 cooling fan will operate at low speed. When coolant temperature reaches 212°F, thermo sensor No. 2 closes and cooling fan No. 1 will operate at high speed while cooling fan No. 2 operates at its one speed.
With A/C control on, compressor on and engine coolant below 212°F, cooling fans No. 1 and 2 will operate. If blower motor voltage is below 9 volts, fan No. 1 will operate at low speed. If blower motor voltage increases to 9 volts or more, No. 1 cooling fan will operate at high speed.
With A/C control on, compressor on and engine coolant above 212°F, both fans operate at maximum speed.