Grand Caravan V6-181 3.0L SOHC (1989)
Thermostat Closed, Cold Engine - With the thermostat closed, coolant flow through the radiator is blocked forcing the coolant to re-circulate
through the block and head. This allows for a rapid warm up. During this time there should be little or no coolant flow through the upper radiator
hose.
Thermostat Open, Warm Engine - Once the coolant has reached normal operating temperature, the thermostat begins to open, allowing coolant
flow through the upper hose and into the radiator. The thermostat will continue to regulate the amount of coolant flow to the radiator to maintain a
"Minimum" operating temperature.
Electric Cooling Fan Operation
The cooling fan ground circuit is controlled by the cooling fan relay. The relay opens and closes to supply or remove ground (-) from the fan.
With the ignition key "ON" positive (+) voltage is constantly supplied to the motor.
The relay is controlled by the cooling fan temperature switch. The switch supplies the ground path for the operating coil within the cooling fan
relay.
When the coolant temperature reaches the maximum set point, the coolant switch closes and grounds the operating coil within the fan relay.
The coil then closes the relay contacts, supplying ground to the fan motor.
When the coolant temperature fails to the lower set point, the coolant switch opens, removing ground from the fan relay. The fan relay then
opens and de-energizes the cooling fan.
