Fan never stops.
Some times the fan starts and does not stop, it's sound like an airplane.
My car has 98777 miles.
My car has an automatic transmission.
Experienced mechanics share their insights in answering this question :
Hey there, thank you for asking about your 2007 Mercedes-Benz CLK550. This is a common symptom of a failing coolant fan relay. This relay controls the cooling fans and cycles them on and off based upon temperature. When this relay is working intermittently or is faulty, it can cause the fans to come on randomly, come on and stay on, or sometimes not come on at all. This can be dangerous in the event they stop working altogether as it can cause the car to overheat. I would recommend having an expert from YourMechanic come to your home to diagnose the problem and replace the cooling fan relay if necessary.
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If the cooling fans are staying on at all times, this is another (less common) symptom of a possible problem with the cooling fan relay. If the relay shorts internally, it may cause power to be permanently switched on, which will cause the fans to run at all times.
The most common reasons for a radiator fan not working can be a blown-out fuse, a bad relay, or a broken wire. The faulty coolant temp sensor might also be a reason behind it. Whatever the case, a dysfunctional radiator fan can be fatal.
On most modern cars, the cooling fan is controlled by the Engine Control Unit (ECU) which gets a signal from the coolant temperature sensor. If it`s not working, the fan won`t turn on when it needs to, which means the engine might overheat.
In normal operation, no, the radiator fan doesn`t run all the time. The fan is hooked to a sensor that measures the coolant temperature in the radiator, and when the temperature gets a little on the high side, the sensor will (basically) send a signal that turns the fan on.
If the fan in your automobile continues to run even after you have shut off the engine of your vehicle, then the coolant in your car may be too low. The water pump is a potential source of leaks and when these leaks occur, your coolant reduces, and this may cause your fan to keep running.
If your furnace fan won`t turn off, you most likely have one of these 3 problems: Your furnace fan limit switch is set to “manual override” The fan limit switch is faulty and needs to be replaced. There`s a problem in your thermostat wiring.
The engine-ECU <M/T> or engine-A/T-ECU <A/T> controls the fan controller to activate the radiator fan motor and the condenser fan motor.
A coolant temperature sensor (CTS) (also known as an ECT sensor or ECTS (engine coolant temperature sensor) is used to measure the temperature of the coolant/antifreeze mix in the cooling system, giving an indication of how much heat the engine is giving off.
If you notice the computer fan running constantly and making an abnormal or loud noise, this might indicate that the computer is not running as efficiently as possible, and/or clogged air vents. It is important to keep dust from accumulating in your computer and ensure adequate ventilation to help reduce heat.
Relevant Questions and Answers :
the most relevant questions and answers related to your specific issue
Radiator fan cycles on once then never again
Hi, thanks for writing in. There is a pressure sending unit that is used by the AC system that runs the radiator fans to maintain proper head pressure (mounted on the top of the accumulator). If this unit is defective, the computer goes into a default mode and runs the fans. I would recommend having an expert from Your Mechanic come to your home to diagnose and repair. I recommend having one of our certified automotive technicians from YourMechanic come to your home or office to inspect, diagnose, and repair the issue.
Car will overheat if I don’t have the fan on. When fan is off it doesn’t come on to release heat from engine. So the fan is always on.
Check the wiring to the coolant temperature sensor and see if there is power to the sensor switch. If there is no power, then check the cooling fan relay and see if its clicking on. If there is no clicking motion, then remove the relay and check for power to the relay. If there is power to the relay, then the cooling fan relay needs replaced. If there is no power to the relay, then check the fuse. If the fuse is burned, replace the fuse. If the fuse is good, then check power from the fuse to the main circuit on the fuse box. If there is no power, then the fuse box needs replaced. If the fan comes on with the air conditioning system switch turned on, that is because the switch overrides the cooling switch to make the condenser cool down to make the air conditioning system work properly.
If you need further assistance with your cooling fans not coming on when the engine gets hot, then seek out a professional, such as one from Your Mechanic, to help you.
(08 f150 4.6L) Truck is cutting off when making a complete stop at red light or stop sign.
Check the Idle Air Control (IAC) valve and see if its dirty or not functioning correctly. I recommend removing the IAC and cleaning it out. If the valve was sticking before, the computer could have caught it and adjusted the idle to accommodate the issue. After having the battery cable off, the computer is in a learning cycle which means that if the IAC is not working properly, the computer will have to relearn and may learn to shut off due to a faulty valve, even though the computer says its good. If you need further assistance with your engine stalling out at stops, then seek out a professional, such as one from Your Mechanic, to help you.
When replacing my fan clutch should I change my cooling fan to a flex-a-light and get a new flex-a-light clutch?
Hi there. It is best to always put on the OEM parts that are required for the vehicle. However, you can get a flex-a-light clutch fan for your vehicle as long as it will bolt up to your water pump pulley and clear the radiator and shroud. I recommend having a clutch design fan for your vehicle and not a fan that spins with the engine all the time. Those fans will cause the engine to overheat on highways and in town especially in hot weather. If you need further assistance with your cooling fan, then seek out a professional, such as one from Your Mechanic, to help you.
Front A/C fan not blowing, but front seat cooling and rear A/C fans are working.
What you are describing sounds like a failure of the blower motor that circulates air in the HVAC system, however, there are certain faults that could occur in the electric circuit that powers the blower motor. If power is reaching the blower motor when the blower switch is in the on position and the blower motor is not functioning as intended then the blower motor is condemned and replaced. On the other hand, if there is no power, then the blower switch and the plug connection on the back of the switch, as well as the rest of the circuit should be inspected. If the circuit includes a blower motor resistor block, of course the resistor block has to be checked for continuity (i.e., specified resistance in ohms) at each position. If equipped with a relay in the circuit, that is easy to test and if the relay works consistently as commanded, you can assume there is no fault there. If you want these diagnostic steps performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request a non functioning blower motor diagnostic/replacement and the responding mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic.
My cooling fan won’t turn on when I turn the ac on. Relays and fuses are good, tested the fan with the battery and it came on??
Hi there. In general, a situation like this occurs when either the thermostat housing or temperature sensor is not relaying the information to the fan motor to activate. However, it’s also possible that there is some electrical short within the cooling system relay’s that is causing the fan motor to not activate when it should. I think the best way to determine the precise source of this problem is to have a professional mechanic come to your location to complete an onsite inspection so they can test all systems to help isolate the root problem and recommend the right repairs.
1992 Honda Accord cooling fans not operating properly.
Hi there. Your issue is the ECT sensor B is not closing the loop when engaged. There is power to the sensor A from the computer, but the sensor B is not connecting when the vehicle is running hot or when the air conditioning is on. I recommend replacing the ECT sensor B, which is the on and off switch for the cooling fans. On the relay, terminals 2 and 4 are the direct circuit for the cooling fan, terminal 1 is the ground, and terminal 3 is for the circuit to the air conditioning system. Check the wiring between the fuse box and the terminal 3 for resistance and see if there is 0.5 ohms or less. If the meter reads OL, then there is a break in the wires and it would need fixed or replaced. If there is 0.5 ohms of resistance or less, then check the A/C switch and the ignition switch as they could be the source of disconnection. If you need further assistance with your cooling fans not working, then seek out a professional, such as one from Your Mechanic, to help you.
Why wont the fan start? Smoking near fan, cooling fan new but wont start. engine overheats.
Hey there. As you alluded, this is a sign of a bad cooling fan relay switch. The cooling fan relay switch comes on when the temperature reaches a certain level to help cool down the radiator. When this is faulty, this will cause the fans to work intermittently or sometimes not at all. This will also obviously cause the car to overheat as well. This part should be located behind the passenger side headlight in a black box with several wires going to a single connector. If you would like to have this taken care of for you, a certified professional from YourMechanic can come to your home or office to inspect the overheating problem and perform any needed repairs.