From L-series RAVE:
As temperature reaches 80-84 °C, the thermostat
gradually opens, bleeding cool fluid from the radiator
bottom hose into the cylinder block and allowing hot
coolant to flow through the heater circuit and to the
radiator through the radiator top hose, balancing the
flow of hot and cold fluid to maintain the optimum
operating temperature. When the thermostat opens
fully, at 96 °C the full flow of coolant passes through
the radiator.
All vehicles have two fans. These operate either in
series or parallel according to engine coolant
temperature or air conditioning requirements. The
fan operation is controlled by the ECM. The fans
operate in series (slow mode) when a temperature
of 106°C or higher is sensed. When a temperature
of 112°C is sensed the fans switch from series to
parallel operation (fast mode). When the
temperature falls to 106°C or below, the fans are
switched back to series operation. The fans stop
when a temperature of 100°C or lower is sensed.