After an engine stop, the fan of cooling of a radiator can continue to work (till 10 minutes). It also can is unexpected start to rotate again even at the switched off ignition.
If the fan of cooling of a radiator does not join at strong rise in temperature of a cooling liquid, check up a safety lock and replace it if it is necessary.
Speed of rotation of the fan of cooling of a radiator does not depend on speed of rotation of the engine, therefore cooling degree cannot be raised having switched to lower transfer.
While the engine works in regular intervals and at movement under a hill speed does not decrease considerably, there is no necessity to include lower transfer.