There are three common symptoms of cooling fan motor relay failure: a cooling fan does not run when it should, does not run at the speed it should, or does not turn off when it should.
If the cooling fan relay has failed, you may see warnings, such as the check engine light and the temperature warning light, pop up on the dash, but first, you may notice that the A/C stops cooling. More about that in the next paragraph. The check engine light illuminating may indicate a faulty cooling fan relay.
The relay is like a light switch,it turns the fan off & on when the timer sends a signal to the relay to open or to close , when it's open it's like having the light switch turned off ,but when it's closed it allows the power to make a complete connection .
your engine overheats; the fans don't start; your air conditioner does not work well or does not work at all; the fan doesn't turn off.
On some platforms, a faulty blower motor relay will cause the blower not to work at all, which means there will be no airflow from the A/C. On others, the blower won't work on “high blow” but all the other speeds will work. The blower motor relay fails because it regularly deals with high current loads.
The engine will stop running, and your vehicle won't move or start. Main relay problems could also lead to your engine running for a while or a very short time. Your vehicle might start normally sometimes but not start at all at other times.
If the radiator fan resistor is shorted, one of the cooling fan modes may not work, the cooling fan may not turn off when the engine is cold, or the cooling fans may not come on at all.
Your car's cooling fan, or radiator fan, plays an important job in keeping your engine cool. Some of the most common causes of a faulty radiator fan include a blown fuse, a faulty temperature sensor, or a defective fan relay. If the fan stops working, your engine could overheat and be damaged.
Coolant Temperature Sensor
Both systems use a temperature sensor to determine when to start the fan. If the temperature sensor is faulty, the control unit doesn't interact with the radiator correctly. Some cars have a separate engine coolant temperature sensor for the radiator fan and the engine control unit.
The average cost for a Radiator Fan Relay Replacement is between $85 and $92. Labor costs are estimated between $27 and $35 while parts are typically priced around $57. This range does not include taxes and fees, and does not factor in your unique location. Related repairs may also be needed.
Location. The coolant fan motor relay in many vehicles is located on a relay block within a plastic case in the engine compartment. This relay block includes other relays and fuses. A diagram on the underside of the case cover maps the location of each fuse and relay.
It could be a problem with the fan motor, temperature sensor, fan control relay, or wiring. The Check Engine Light might come on. With modern cars, a DTC will be triggered that illuminates the light on the dash when it exceeds normal operating temperatures. It might be accompanied by a message on the cluster too.
If your radiator's cooling fan stops working, your engine could start to overheat and might even break down.
If the fuse is blown, the air conditioner will quit working and you'll need to have your AC repaired.
The radiator fan is a type of fan used in automobiles to cool the radiator. By doing so, it helps with regulating engine temperature. It's, therefore, also known as the engine cooling fan and usually mounted between the radiator and engine. In some vehicles, the fan sits between the grille and the radiator.
The fan stops blowing air: Anyone who has driven a car will realize that there is a problem when the fan isn't running when the air conditioning is on. If the cooling fans are not running at all, then this may be a sign that the fan control module is damaged.
Blower Motor Resistor Test
Typically, if the fan will work on some speeds but not on others, the resistor is suspect. Okay, let's say there's no melting going on, but your fan doesn't work on all speeds. Typically, if the fan will work on some speeds but not on others, the resistor is suspect.
Signs of Trouble: Watch out for wobbling blades, unusual noises, or sluggish fan speeds. These could indicate worn-out parts, loose connections, or a failing motor, all signs it might be time for a replacement.
Recurring Clicking Noise When Turned On: The relay might struggle to work before the system fails, causing a clicking noise. There will be constant effort to deliver power to the compressor before the relay fails. These power spikes allow the compressor to turn on, but not enough to keep running or generate cool air.
In AC systems, the air conditioner reset button is on the outside unit's lower edge, typically close to the ground. Some models have the reset button located behind the service panel, which may require tools to remove. Reset buttons are usually red or yellow with a clear “reset” label.
Weak or Reduced Airflow: Another symptom of a faulty blower motor relay is reduced airflow. You may experience weaker air coming from the vents, even if the blower motor is running. This can lead to inadequate temperature control and discomfort in the room.