Radiator fan - check
If the T4 engine is overheating due to the fact that the fan does not turn on, then the first thing to check is the fan thermal switch located on the side of the T4 radiator.
♦ Start the engine and let it run until it warms up or the T4 radiator fan turns on.
♦ Carefully open the cap of the expansion tank so that steam can escape.
♦ Insert a thermometer into the expansion tank. At a temperature of 84-89ºС, the fan should turn on at medium speed, at 93-98ºС - at full power. If this is not the case, remove both electrical wires from the thermal switch terminals and connect them together, turn on the ignition. The Volkswagen Transporter T4 fan should turn on immediately. In this case, replace the thermal switch and repeat the test. If the fan still does not turn on, check the wiring, fuses and motors.
Components of the T4 engine cooling system . Coolant replacement .