THE COOLING FAN RELAY ESSENTIALLY FUNCTIONS AS, THE ON/ OFF SWITCH FOR THE ENGINE’S COOLING FANS.
And, is therefore an important electrical component, of the engine’s cooling system.
As a result, most cooling fans use electric motors. And, they have a moderate to high current draw. But, using a cooling fan relay, solves this problem.
So, when the correct parameters are met. Then, a temperature switch or the computer, will activate the cooling fan relay.
COOLING FAN RELAY, WHAT DOES IT DO
A relay uses a relatively small electric current, that can turn on or off, a much larger electric current. So, a relay is basically an electromagnet. For instance, a coil of wire that becomes a temporary magnet, when electricity flows through it. You can think of a relay as a kind of electric lever. Switch it on with a tiny current. Then, it switches on, another item using a much bigger current.
Why is that useful? As the name suggests, many sensors are incredibly sensitive pieces, of electronic equipment. And, produce only small electric currents. But, often we need them to drive bigger pieces of equipment, that use bigger currents. As a result, relays bridge the gap, making it possible for small currents, to activate larger ones. This also includes, the fuel pump relay.
COMMON FAILURE SYMPTOMS:
Engine Running Hotter Than Normal
An engine that runs hot or overheats. This is one of the first symptoms commonly associated with, a bad or failing cooling fan relay.
Cooling Fans, That Will Do Not Come On
Another common symptom is when, the fans don’t come on at all. So, if the cooling fan relay fails, it will be unable to supply power to the fans. As a result, the fans will not operate.
Cooling Fans, That Will Not Turn Off
This is another (less common) symptom of a bad or failing cooling fan relay, but it does happen. Cooling fans that run all the time, and will not turn off.
ENGINE COOLING FAN, HOW TO TEST IT
The fasted way to tell whether or not the electric fan(s) are working is, to start the engine. Then, let it reach normal operating temperature, and then turn the A/C on. The cooling fan in the engine compartment, should turn on to pull air through the radiator and A/C condenser.
On Many Vehicles, There May Be Two Fans:
- A main cooling fan, for the radiator.
- A second fan, for the condenser.
Both Fans Should Come On When The A/C Is On.
If one or both fans fail to come on. Then, the lack of additional cooling provided by the fan, may cause poor A/C cooling performance. Also, it may cause the A/C compressor to overheat and fail. The engine may also, run hot and overheat.
PROBLEMS IN THE COOLING FAN RELAY CIRCUIT
The typical electric cooling fan circuit includes, a temperature sensor, a relay, a control module and the fan motor. The relay is the component that fails most often. So, be sure to test the relay, as well as its power supply and ground connections.
A good relay coil will typically read 40 to 80 ohms. If resistance is high, the coil may still be working. But, it is failing or it may not work, when electrical loads are high. If the coil has no resistance, it is open and has failed. Replace the relay.
Another simple relay test is, to shake it. If you hear something rattling inside, the relay armature is probably broken.
THERE ARE THREE BASIC TYPES OF RELAYS:
1- Normally open
The armature closes, when the coil is energized, to route power to the fan motor.
2- Normally closed
The armature is normally closed. And, is pulled open, when energized.
3- Dual relay
This type conducts current, when open and when closed, in two different circuits.
CONCLUSION
The cooling fan relay essentially functions as, the switch for the engine’s cooling fans. And, is therefore an important electrical component, of the engine’s cooling system. Finally, if you suspect that your cooling fan relay, may possibly be having issues, have it checked. Basic Testing For Any Relay.
BY DANNY BENDER
