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Re: Car overheating, fan won't turn on.
Well first you will need to hard wire the fan to the battery to determine if the fan is good. then You will need to check the fuse/relay for radiator/AC fan. after that if necessary, check the engine coolant temperature sensor, could be faulty, this sensor tells the computer when the engine is hot enough to turn the fans on
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Temperature Warning Light is on Inspection Service How this system works:
With the exception of older, air-cooled vehicles, cars rely on a liquid called coolant (or antifreeze) to keep the engine at an optimal temperature. Coolant is a mixture of water and ethylene glycol, and it circulates around the engine block and absorbs excess heat, which keeps the engine from overheating. The coolant converts that heat to air in the radiator, and then the air is emitted, at which time the coolant is ready to absorb more heat. Without coolant, the engine would quickly ruin itself with its own heat production.
Common reasons for this to happen:
Coolant is low or weak: The most common culprit when an engine overheats is low or weak coolant. If your car doesn't have enough coolant, then it can't absorb enough heat. While your car will naturally lose small amounts of coolant over the years, a leak is the most likely cause of low coolant levels.The proper ratio of coolant to water can also get distorted, resulting in a problem. Too little or even too much antifreeze can dramatically lower the boiling point of the coolant. A proper ratio of antifreeze to water is 50/50 to 60/40, depending on the vehicle.
Broken radiator fan shroud: The radiator fan shroud directs the airflow across the radiator so the air can absorb the coolant's heat. When the fan shroud breaks or becomes dislodged, air fails to enter the radiator, and the coolant will no longer have a place to direct the transfer of heat.
Broken or missing air dam: Along with the shroud, some vehicles have an air dam (or deflector) underneath the vehicle. If this is broken or missing then the air can pass underneath the vehicle but not also through the radiator, which will cause overheating. These air dams are essential in newer vehicles, as they force the air through the fan shroud.
Faulty coolant temperature sensor: The temperature sensor takes constant readings of the coolant temperature and sends that information to the engine control unit. Based on the temperature of the coolant, the engine control unit adjusts the ignition timing, the fuel injector pulse, and the operation of the electric cooling fan.
Bad water pump: The water pump is responsible for keeping the coolant cycling throughout the engine. After the coolant transfers its heat energy to the air, the water pump recirculates it around the engine so that it can absorb more heat. The most common water pump problems are a leaking pump, bad bearings, or an impeller that has rotted away due to a low coolant ratio.
Stuck thermostat: The thermostat acts as a dam for the coolant. When the engine first turns on, and it is still cold, the thermostat keeps the coolant from circulating, which allows the engine to warm up as quickly as possible. Once the engine has reached its operating temperature, the thermostat opens and allows the coolant to circulate. A stuck thermometer may stay permanently sealed and therefore keep the coolant from reaching the engine block.
The thermostat may also stick open. This will not usually result in overheating, but it will waste gas.
Broken engine cooling fan: The engine has a cooling fan that is deployed when the coolant needs some extra help. When the coolant temperature sensor notices that the coolant temperature is getting too high, the engine control unit (on newer vehicles) will initiate the cooling fan to reduce the temperature.
Broken thermostatic fan clutch: Older vehicles use a thermostatic fan clutch to engage the engine cooling fan, which is mounted to the fan blades. The fan clutch uses a bi-metallic spring that tightens when the temperature increases. This acts as a "high speed" option for the fan, and when engaged, it draws more air across the radiator.
Blown head gasket: The head gaskets sit between the engine block and the cylinder heads, and keep coolant from entering the engine's oil and combustion chamber. When a gasket blows and coolant seeps in, the issue is not only that the engine will overheat, but also that damage may be done to the catalytic converter and oxygen sensors due to contamination from the coolant.
What to expect:
A top-rated mobile mechanic will come to your home or office to determine the cause of the temperature warning light turning on and the source of the overheating, and will then provide a detailed inspection report that includes the scope and cost of the necessary repairs.
How important is this service?
An overheating engine is extremely dangerous. It is not safe to drive a vehicle with an overheating engine, or you may ruin the engine completely and put yourself at risk. As soon as you notice the light come on, pull over. If there is no place to safely pull over, turn off your radio and other electrical units, and turn your heat on high (this will funnel some of the hot engine air into the cabin). As soon as you can safely pull over, do so, and then book one of our mechanics to perform an inspection.
It is pretty hard to TS this type of trouble without being in front of the car.
Try to turn the air conditioner on, and check if the fans or fan comes on. This will give you an idea if the problem is the sensor or the fan it self. If the fan does not comes on, then it is probably the fan. Also, you can test the fan by connecting it directly to the battery. This will also let you know if the fan is in working condition or not.
Now, if the fan is not working, there is no warning about it hen overheating, then it could be the sensor, have it check by a professional.
The fans are normally thermostatic - which means they only operate above a certain air temperature. If the air coming across the radiator is below a pre-determined temperature, they will not operate.
If the temperature gauge was only half way they may not have reached the required temperature to turn on.
When you are travelling the movement of the car usually provides enough air across the radiator to keep it cool enough - when you stop and they is no moving air, the fans will normally come on then.
Sounds like your radiator fans are not coming on when the car gets hot. When the A/C is on the fans cycle on/off with the A/C pump so it keeps the fans on. Your engine temp sensor or fan sensor might be bad. Check the connections on the sensors and fans for water/corrosion too.
replace your thermostat and check the waterpump. The ac "pulls" heat out of the air in the car thereby making it cooler, at the expense of making your coolant heat up even quicker than normal. Try this to see what's going on.. Open the radiator cap, start the engine and wait until the car gets up to operating temperature. You should be able to see the water circulating through the radiator...if the fan comes on, and the water isn't moving, then replace the thermostat. If it still isn't moving after that, the water pump may be no good. Id bet on the thermostat. They're cheap and need to be replaced every so often. If the water is circulating and the fan never turns on, then you check the fan motor, relay, etc. There is also a temperature sensor located somewhere next to the thermostat. It's rare to have to replace that, but if it's faulty, then the fan won't turn on and thus overheating occurs. I am assuming here that if you drove your car up a hill without the ac on, it will overheat or get hotter than normal...So....go test your circulation first and let me know what you find. Oh yeah, when you do the circulation test, turn your heater in the car on full blast too...does it get hot inside the car?
Most cars have an 2 electric fans on the radiator. One will run when the coolant gets hot and the other will run when there is more cooling demand OR it will run when the AC is turned on. My guess is, the second fan is not running when your AC is. Your AC system creates heat of its own. The heat is removed through the condenser (radiator-like coil) which is usually located in front of your engine radiator. Without a fan the heat is transferred into your engine radiator causing it to over heat. This would explain why it overheats while idlling and not while driving. While driving, air is flowing through the radiator and condenser. to provide the necessary cooling. In short, check to see if both fans are running when the engine is hot and the AC is turned on.
Blow out the radiator core from the engine side with compressed air to remove bugs and other debris. Make sure the cooling fan comes on when the engine gets to operating temp. If the car car has AC, turn it on which should start the fan immediately. If no fan action, try to turn the fan blade(s) which should turn easily with no noises. Check the fan fuse and fan relay. If the fan(s) come on fine, check the coolant level in the radiator core--it should be right at the top. Check the seal on the cap and replace it if it is decayed or damaged. Make sure the reservoir bottle is filled to the line and the connecting hose is in good shape. It is possible that the thermostat is sticking and not opening fully. Also, check the intake and outlet hoses to and from the radiator for firm condition without decay, collapse, or other damage. A hose can sometimes peel away a portion of the hose interior which can cause blocking. Hope some of this helps!
1. "When idle, the fan is not working" It should only work when the temperature reaches about 200 degrees. When idling it take some time to reach this temperature. Turn the air condition on and the fan will start right away. If you turn the Air Condition on and the fan do not start then, the fan may be bad or the temperature sensor is bad. The two wire beside the battery I would have to see it and try to determine where it go or supply before I can advise you. If you are concern that these wires are the power supply for the fan then that can be tested to find out. I hope this help you.