Knowing What is Wrong with Mercedes Benz E320 Electric Cooling Fan
A Mercedes Benz E320 electric cooling fan keeps the temperature of the engine coolant and antifreeze from rising above the operational temperature. It pushes or pulls air through the radiator core. It is usually off when the engine temperature is within the predetermined level and comes on when there is an increased load on the cooling system such as running the air conditioner. A bad electric cooling fan, however, can make the engine overheat if it does not turn on at the right time. Here are some tips you can follow to identify what is wrong with your car's electric cooling fan:
Check the fan circuit.
To check the fan circuit, start the engine and turn the A/C to maximum. Observe if the fan runs. If it does, the fan motor, relay, fuse, and wires are fine. Another way to check is by using a voltmeter or a test light on the fan's wiring connector. When the engine is hot and the A/C is turned on, you should be able to observe voltage. Otherwise, the fan has gone bad. Still another way to check is to jump the cooling fan directly to the battery. In this case, if the fan runs, the motor is good, but the problem may lie on the wires, the fuse, or the control circuit. If it does not, check the wires, fuse, and control circuit. And if you find them working properly, then your fan motor needs to be replaced.
Check the temperature at which the fan comes on.
To perform this check, turn off the A/C and let the engine reach its normal operating temperature. The fan would normally go on at 200 to 230 degrees. If it doesn't, a resistance check should be made on the temperature sensor or the switch. Also, check the voltage on both sides of the relay.
Check for noisy bearings.
When the fan does turn on after your Mercedes' engine reaches its operating temperature, but its bearings make a lot of noise, it indicates that the motor is worn. Aside from this, you will also be able to observe that the fan turns quite slower than it used to.