My car cooling fan works for a few seconds when I turn the car off, not on when the car’s on. Is the temperature sensor bad?
My car cooling fan works for a few seconds when I turn the car off, not on when the car's on. Is the temperature sensor bad? The radiator also leaks
My car has 136000 miles.
My car has an automatic transmission.
Experienced mechanics share their insights in answering this question :
If it doesn’t run for more than about a minute, that could be a normal situation. The fan is triggered by temperature at the cylinder head, and when the engine is off and the coolant isn’t circulating, the heat rises to the top of the engine. If the car is fully warmed up and it’s a hot day outside, the fan may come on for a short time when the car is off. If it runs on and on, it may be a different matter and you will want to have it checked out.
The leak, should concern you. Left to themselves, things always go from bad to worse and it could get worse at a very inconvenient time. If you contact Your Mechanic, they can send a technician to your home or office to check out your Honda and let you know what can be done for it.
The leak, should concern you. Left to themselves, things always go from bad to worse and it could get worse at a very inconvenient time. If you contact Your Mechanic, they can send a technician to your home or office to check out your Honda and let you know what can be done for it.
How to Identify and Fix Common car Problems ?
Our sources include academic articles, blog posts, and personal essays from experienced mechanics :
Radiator Fan Works Intermittently
The cooling fan works intermittently causing occasional overheating problems. This happens when you have a defective control module, loose connectors, or faulty sensors. To pinpoint the problem, check the sensors for resistance using a digital multimeter.
Get your radiator and ac condenser cleaned with a pressure washer. Repeated kicking of fans occurs because the condenser alone is not able to dissipate heat owing to dust accumulation.
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.
If the fan comes on, you may have a bad temperature sensor or gauge. A cooling fan temperature switch (or sensor, in some vehicles) can also get stuck, which may cause the fan to run continuously any time you turn the ignition key on or start the engine. Troubleshoot the switch.
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.
If little air is coming through the vents (hot or cold), then it could be because the blower motor for the fan or a switch or resistor that controls fan speed isn`t working. Another cause might be that the electronically controlled “blend doors” that direct air flow are stuck or broken.
Your radiator fan should kick in at about 200 degrees Fahrenheit. If you notice your vehicle is overheating or at the very least running hotter than it normally does, listen for the fan to see if you can hear it.
Temperature sensor
The sensor reads the system`s temperature and determines when to turn the fan on. If it isn`t functioning properly, chances are that the fan won`t turn on, and the vehicle may overheat as a result.
A cooling fan relay is used on vehicles that have an electrical fan to cool the engine. The function of the cooling fan relay is to convert a low voltage signal from either the electronic control module (ECM) or a thermostatically controlled sensor.
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.
There are two temperature sensors in some vehicles, one to send information from the engine system to the control unit and another from the control unit to the dashboard. The device follows the principle of dependence of potential difference in temperature.
Depending on the type of radiator fan your car has, it may be powered by a built-in electric motor or directly by your car`s engine. Either way, it uses a thermostatically-controlled device that turns on the fan when the coolant reaches its safe maximum temperature.
One of the first symptoms of a problem with the blower motor relay is a blower motor that does not function. As the relay is the switch that supplies current to the blower motor, if it fails internally, then power may be cut off from the blower motor circuit causing the motor to no longer function.
Poor ventilation can cause dust and heat to get trapped inside the case of the motor. This can cause your fan to stop functioning—especially if your fan has an overheating feature that causes it to automatically shut off if it gets too hot.
It`s normal for some vehicles to have a fan run for a few minutes after the car is shut off, generally to keep the engine cool. However, if the fan is running for an extended period, the fan itself can become damaged due to overuse.
The Thermocouple As A Temperature Sensor. The Thermocouple is by far the most commonly used type of all the temperature sensor types. Thermocouples are popular due to its simplicity, ease of use and their speed of response to changes in temperature, due mainly to their small size.
Cooling fans stay on at all times
If the relay shorts internally, it may cause power to be permanently switched on, which will cause the fans to run at all times. Depending on the wiring setup of the vehicle, this may cause them to stay on even when the vehicle is off, which will drain the battery.
It`s supposed to turn on before the engine overheats. The fan shouldn`t run constantly, but it is supposed to switch on at a specific temperature (the exact temperature varies from car to car, as different engines have different operating temperatures) to cool the engine down before it gets dangerously hot.
Blower resistors are resistors which are used to control the fan speed of automotive blowers. The fan speed can be changed either by switching the blower resistor resistance mechanically using a rotating lever, or electronically by the air conditioning system.
Fan speed is controlled with thyristor or transformer speed controllers. Thyristor speed control. Thyristor speed controllers provide smooth manual motor speed control and air flow control respectively. Operation of the thyristor speed controllers is based on output voltage control with a triac voltage regulator.
Most electric cooling fans get their power from an ECM-controlled relay.
The engine coolant is overheating if it`s around 240 to 250 degrees. This is a critical light! It means your engine is beginning to overheat.
The fan setting on your thermostat controls your HVAC`s system blower. The blower helps circulate hot or cold air throughout your home until the temperature on the thermostat is reached. There are two settings on your thermostat to control the fan – auto or on.
Relevant Questions and Answers :
the most relevant questions and answers related to your specific issue
My car cooling fan works for a few seconds when I turn the car off, not on when the car’s on. Is the temperature sensor bad?
ANSWER : If it doesn’t run for more than about a minute, that could be a normal situation. The fan is triggered by temperature at the cylinder head, and when the engine is off and the coolant isn’t circulating, the heat rises to the top of the engine. If the car is fully warmed up and it’s a hot day outside, the fan may come on for a short time when the car is off. If it runs on and on, it may be a different matter and you will want to have it checked out.
The leak, should concern you. Left to themselves, things always go from bad to worse and it could get worse at a very inconvenient time. If you contact Your Mechanic, they can send a technician to your home or office to check out your Honda and let you know what can be done for it.
The leak, should concern you. Left to themselves, things always go from bad to worse and it could get worse at a very inconvenient time. If you contact Your Mechanic, they can send a technician to your home or office to check out your Honda and let you know what can be done for it.
When I turn on my AC the radiator fans do not turn on. The fans do come on when the car warms up so I know they are working and the fuses are good. The AC compressor does come on and the air blows ice cold when the car is moving. Car is a 2006 Chrysler Sebring Sedan 2.7l v6.
ANSWER : The control circuit for the fans needs to be checked. For example, there is usually a condenser fan relay in the A/C electrical controls. There could be a fault with that relay and/or wiring problems, perhaps even just a loose connection, blown or loose fuse, and so forth. To resolve something like this, the recommended service is an electrical component diagnostic. If you request that diagnostic service, the responding certified mechanic will get the problem pinpointed and resolved. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.
Just replaced head gasket, changed crack sensor new plugs. The check engine light is on, but dim, the only other light that the dash is a normal battery indicator. The fuel pump is not running when switch is turned on, the power windows don’t work, it turns over but not firing. It’s like only one part of the system is working. Also the heater fans work even if the switch is off.
ANSWER : I would first look at the diagnostic trouble codes. Those codes are available because the check engine light is on. If the fuel pump is not running (momentarily) at key on, that fault alone will prevent the car from starting as there will be no fuel pressure. Pump output and pressure can be directly tested and you can also check for electrical power to the pump. To find out why the engine will not run, the recommended diagnostic is a no start diagnostic. If you request that service, the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.
Cooling fans is not working. Replaced the temperature sensor and the fan is still not working. Disconnect the sensor harness and the fans works.
ANSWER : Hi there. There could be an issue with the electrical wiring to the fans from that connect to the coolant temperature sensor. Check the wiring for any loose connections or any corrosion that could keep the sensor from making a connection to the fans.
For the engine stalling only when hot, there could be an issue with the coil packs getting too hot. Check the condition of the coil packs and see if the harness is plugged in correctly. Make sure that the coil packs are mounted away from any additional heat source. If the coil is getting too hot, then the windings are expanding causing a break in the current making the coil stop generating a voltage making the engine stop running. When the coil cools down, the windings colaps and cause them to create the voltage needed to make a spark. I recommend seeking out a professional, such as one from Your Mechanic, to help you diagnose your stalling issue.
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??
ANSWER : 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.
Cooling fan malfunction
ANSWER : Hello there. The cooling fan running when the vehicle is shut off for this vehicle is fairly common. In some cases the cooling fan will run when the vehicle is turned off to continue to cool it down for a few minutes. In this case though, the cooling fan running sounds excessive. This vehicle has a high chance of the A/C high pressure sensor failing, which causes the fan to stay on as well. Other possible causes are the thermostat or a cooling fan relay. If the problem persists, I recommend having a qualified technician, such as one from YourMechanic, come to your home or office to diagnose the cooling system and perform any repairs required.
Okay so when I turn my lights on at night my brake lights do not work, when I don’t have my lights on they work fine.
ANSWER : Hi there. Based on your inquiry, it’s highly probable that you have a damaged light switch or some electrical fault inside the turn signal relay. However, it’s also possible that the brake switch above the brake pedal could also be the source of your problem. Due to the fact that multiple electrical components might be causing this issue, it’s a smart idea to first have a professional mobile mechanic complete a brake lights are not working inspection, so they can determine what’s causing all of these issues and recommend the right repairs.
Radiator fans wont turn off unless I turn off the car, why?
ANSWER : It sounds like you have checked just about everything that controls the fans other than the fan power relay itself. As you may know the coolant fan relay turns the fans off and on by receiving information from the coolant temperature sensor at specific temperature thresholds. When this relay is not working properly, this can cause the fans to come on intermittently, stay on all the time or sometimes not at all. When this happens you will notice a temperature spike and drop occasionally as the fan comes on and off. I would suggest having an expert from Your Mechanic come to your home to diagnose your coolant fan.
