Quick Answer: What Causes Cooling Fans Not To Come On?

Should radiator fan turn on when AC is on?

Both radiator fans should always run when the AC compressor is engaged.

Both radiator fans should always run when the coolant temperature sensor in the bottom tank of the radiator reaches about 212*F..

What causes a car fan to run constantly?

It is possible that this problem of your car’s fans constantly running is some sort of mechanical or electrical error from a poor sensor or other component. There are temperature sensors and some cars have separate sensors for the gauge itself. … The fan can be shut off when the engine temperature warrants.

When should the radiator fan kick on?

Most fans should come on when the coolant reaches about 200 to 230 degrees. If the fan does not come on, something in the control circuit is defective.

What are the symptoms of a faulty cooling fan switch?

Several symptoms may point to a bad or failing thermo coolant fan switch.Engine overheating. Engines generate an enormous amount of heat and as a result are subjected to very large temperature swings if this switch does not operate effectively. … Check Engine Light comes on. … Broken or shorter signal wire.

Does the coolant temp sensor control the fan?

The sensor works by measuring the temperature that’s being given off by the thermostat and/or the coolant itself. The temperature is then sent to the on-board control system. … As the control system receives the temperature from the CTS, it may trigger the cooling fan to either shut off or turn on.

Should radiator fan run all time?

An electric fan SHOULD NOT run all the time. A mechanical fan WILL spin as long as the engine is running, but it will only ‘lock up’ when needed.

What temp should cooling fan come on?

about 200 degrees FahrenheitWhat Temp Should My Fan Kick In? 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.

What controls the radiator fan?

A mechanical fan is connected to the engine directly by drive pulleys. This type of radiator fan is controlled by a thermal fan clutch that senses radiator heat. After sensing the heat temperature, the radiator fan turns on when the engine is running at a higher temperature.

Why does my cooling fan keep coming on?

The fan turning on is normal and a consequence of the hot coolant, not a cause. … The coolant may not be moving due to a water pump problem, blockage in the radiator or hoses, or a stuck valve, i.e., the “thermostat” in the coolant line. Alternatively, the fluid level may be low.

Why does my radiator fan not turn off?

A common problem vehicles experience is a cooling fan that doesn’t kick on and off when it’s supposed to. … The first is the fan relay, which due to age or corrosion will stop switching the fan on and off. The second is the fan switch itself, the sensor which tells the relay when to activate the fan.

What are signs of a bad thermostat?

There are several common symptoms associated with a bad or failing thermostat that will alert you that service is due.Temperature gauge reading very high and engine overheating. … Temperature changing erratically. … Coolant leaks around the thermostat housing or under the vehicle.

How do I know if my thermostat is broken?

The most common signs of a broken thermostat are:Thermostat display is off or is non-responsive.Turning on the heat or AC does nothing.The heat or AC will come on, but either stays on nonstop or cuts out before the temperature setting is reached.

What happens when the coolant temperature sensor goes bad?

If the coolant temperature sensor goes bad it can send a false signal to the computer and throw off the fuel and timing calculations. It is not uncommon for the coolant temperature sensor to fail and send a permanently cold signal to the computer. … This will reduce fuel economy, and may hinder engine performance.

What tells the cooling fan to come on?

When the engine temperature approaches unsafe levels, the vehicle’s computer or temperature switch turns on the cooling fan relay. The activated relay completes a circuit, allowing an electric current to flow through it and reach the cooling fans.

Why is my radiator fan so loud?

If people hear your fan coming before they hear your engine, you definitely have an excessively loud fan. … Worn bearings, bent or broken blades, and unbalanced rotating assemblies can cause a fan to screech, howl, or otherwise make noises it shouldn’t.

Can a bad thermostat cause fan not to come on?

If the thermostat is stuck open (allowing coolant to flow) it can cause the engine to run cooler than normal so obviously the fan wouldn’t come on…..but not like the engine/coolant can be running too hot and the thermostat somehow effects the sensor reading or operation of the fan.