Family Cars Information

Jetta Engine cooling fan troubleshooting

Control Schematic

Jetta radiator fan motors are static, low-speed and high-speed three stalls. When the engine compartment temperature is above 70 ℃, the temperature switch will automatically file the circuit connected to low-speed radiator fan, fan rotation, so that the engine compartment temperature drop, when the temperature dropped to below 70 ℃, the temperature switch off the circuit, the fan stops rotation. In the radiator outlet Department, equipped with a thermal switch 3 (also known as dual-temperature and temperature switch) to control the fan rotation and speed. When the engine coolant temperature is below 85-91 ℃, the fans are not turning, the natural airflow through the radiator, when the radiator water temperature (engine inlet temperature) to reach 92-96 ℃, the radiator fan low profile switch is closed, with low stall speed fan operation; when the radiator water temperature of 99-105 ℃, the starter relay 4 connected to the fan speed running at high speed stall. 

Failure

The engine overheating, coolant temperature warning lights flashing, coolant level, water pumps Deng Jun normal, there is no radiator and its connecting piping hot and cold non-uniform phenomenon. Start the engine, and running to the coolant temperature warning light flashing after, it was discovered that only low-profile radiator fan did not speed file.

Failure analysis and verification

Because there are low-speed radiator fan did not speed, it concluded that low-speed fan motor and thermal switch file no problem, the failure may be out of the thermal switch or the starter relay on a high-speed file. Unplug the radiator fan thermal switch and thus on the three outlets, with wires to connect the red wire then then-chu-chu with the red and black lines, fans are still running, the interruption in the starter relay. 

Profile measurements with the multimeter’s ohm starter relay 4 by heat-sensitive switch and a red and black lines Datie next column next column, there is no resistance shown, indicating starter relay wire circuit occurs. 

Replacement starter relay 4, the start engine testing, troubleshooting.