Plumbing

The coolant circulation pump is used to maintain a uniform flow of coolant through the heater core even at low engine speeds and in the residual engine heat utilization mode (R.E.S.T).

FUNCTION IN HEATING MODE
The quantity of coolant pumped into the heater core with the engine running depends on the coolant pump. The coolant circulation pump ensures that the water flows through the heater core uniformly without bubbles even at low speeds. The coolant circulation pump is controlled by the A/C heater control module.

FUNCTION WITH RESIDUAL ENGINE HEAT UTILIZATION
The coolant circulation pump, pumps the heated coolant to the heater core when the engine is OFF. When the R.E.S.T button is pressed the temperature is controlled by the A/C heater control module (in the same manner as when the ignition is ON). The A/C heater control module switches the electric motor for the coolant circulation pump which drives the impeller via a magnetic clutch.