| I've seen quite a few electric cooling fans give up | | | | check for power and a good ground at the motor |
| the ghost recently. The complaint from the driver | | | | itself. I have also seen mechanics take their |
| is usually the air conditioning is not working. | | | | power probe and supply 12 V to the fan motor |
| Although some owners may notice a car | | | | to see if it runs. I have also seen and used the |
| overheating condition. In either case, one of the | | | | tap test where you just use the handle of a |
| first things that a mechanic will check is to verify | | | | screwdriver to tap on the back of the electric |
| that the electric cooling fan is running when it is | | | | motor. |
| supposed to be. | | | | Note that a qualified mechanic should conduct |
| The overall efficiency of a car's cooling system is | | | | these tests. The cooling fan can be a dangerous |
| based on the amount of heat that can be | | | | car part. If a fan motor tests good then you will |
| removed from the cooling system and | | | | have to check the other side of the circuit. This |
| transferred to the air around it. At highway | | | | consists of a cooling fan temperature switch and |
| speeds ram air through the radiator is sufficient to | | | | a fan relay. |
| maintain proper cooling. | | | | The temperature switch could be located in a few |
| When the engine is idling or the vehicle is at very | | | | different places. But often they are mounted near |
| low speeds. The engine's cooling system needs | | | | the thermostat. The coolant temperature switch |
| additional airflow. On modern cars an electric | | | | is a simple on or off switch that sends power or |
| cooling fan delivers this air. | | | | ground to the cooling fan relay. |
| The use of this type of fan eliminates the power | | | | This should not be confused with the coolant |
| drain during times when fan operation is not | | | | temp sensor for the computer, which on many |
| needed. Although there are vehicles still | | | | vehicles is separate. When the engine coolant is |
| manufactured with belt driven fans, they are not | | | | below 230° or so. The switch will remain |
| as efficient or used as often as electric fan | | | | open and the fan will not run. When the |
| motors. | | | | temperature switch senses the engine to be over |
| In most late-model applications electric fans save | | | | 230° the switch closes. This energizes the coil |
| power and reduce the noise level of the vehicle. | | | | in the relay, closing the contacts and sending 12 V |
| It's hard to say how long one of these units will | | | | power to the cooling fan motor. |
| last, because it depends on the vehicles operating | | | | The above is common example of a coolant fan |
| conditions. Even though modern fans are well | | | | motor circuit. Some vehicles may have more |
| sealed they are still made with metal parts that | | | | complicated systems. Some car makers will even |
| can wear and corrode over time. | | | | use the ground side of the circuit to control |
| When I have one of these cooling fan motors to | | | | operation of the fan. |
| diagnose I will often go right for the source and | | | | |