Cooling Fans Only Work When Temp Sensor Is Unplugged

When a Cooling Fans Only Work When Temp Sensor Is Unplugged, what’s off-base?

On the off chance that your cooling fan only works when the temperature sensor is unplugged, there are two normal causes and two normal answers for this issue.

How about we investigate these causes and answers to get you back on track with the cooling framework in your vehicle again?

A coolant temperature sensor is a vital part of an automobile motor’s cooling framework. Without an appropriately operating cooling framework, the motor will run hot, which will cause the motor to operate wastefully and may bring about genuine damage.

The coolant sensor is a thermometer that reports the internal motor temperature to the motor’s control PC.

Information from the sensor is used by the PC to make adjustments to the fuel infusion framework, start timing, and other motor parts.

Fans Only Work When Temp Sensor Is Unplugged

The cooling fan is used to blow air across the radiator, which assists with accelerating the cooling of the radiator and the motor inside it.

The cooling fan is switched now and again as required by the motor’s control PC based upon information from the coolant temperature sensor.

A faulty coolant temperature sensor may bring about a fan not being as expected used, which may cause the motor to overheat.

The coolant temperature sensor regulates the internal temperature of the ignition motor.

Initialized in OBD (on-board diagnostic) and OBD II (vehicles manufactured from 1996 and then some), the sensor is inundated in the coolant framework to screen the coolant assurance level.

Low coolant won’t give sufficient temperature security to adequately control the internal heat. Thus, the ECT sensor can be compromised.

Coolant Level Sensor Located

Coolant level sensors assist with observing coolant in a car’s motor, and these gadgets also send a large group of information to the vehicle’s PC.

The location of the sensor varies from one model to another, and a few cars may have multiple.

The location of the coolant sensor varies according to the manufacturer and model of the vehicle.

A typical configuration places the coolant sensor inside the intake manifold, yet a few manufacturers place the sensor inside the chamber head. All sensors are situated so one tip contacts the motor coolant.

Coolant sensors use a temperature-delicate resistor. This resistor remains profoundly resistant at cool temperatures, yet resistance drops as the coolant temperature rises.

Assuming that the sensor loses contact with fluid coolant, it conveys a fault message to the PC and triggers an indicator light.

Cooling Fan Working

On the off chance that the cooling framework in your vehicle uses an electric cooling fan, probably you have a transversal (sideways) mounted motor.

Some longitudinal (front to rear) mounted motors use the electric fan as well.

However, they usually have a motor-controlled cooling fan. The electric cooling fan uses an immediate flow (DC) electric engine with a Thermo switch, module, or PC control to turn it on or off, contingent upon coolant temperature or AC operating condition.

On more seasoned fan circuits, the thermostatic switch interfaces with battery power on one side, and to the fan engine on the other.

In most ’90s and more up-to-date models, the control was passed to the car PC or a dedicated module.

For example, when coolant temperature changes, the Thermo change reports this change to the PC through a voltage signal, which the PC or module uses to activate the cooling fan through a fan relay.

An electric cooling fan, not just assists save energy by running only when the framework needs to with eliminating abundance heat away from the motor, but assists safeguard other touchy circuits and electronic parts from the heat with damaging.

Throughout the cold weather months, your radiator fan saves considerably more energy when enough cool air moves through the radiator on the highway.

Regardless of whether your cooling fan doesn’t have a complicated circuit, you need to know where to look when your fan doesn’t function as expected.

Next are some fan circuit central issues you want to look at when diagnosing issues with your electric cooling fan.

Reasons Of Radiator Fan Is Not Working

Blown Fuse

A breaker upholds almost everything electrical in a car. Assuming there is an electrical flood going towards a piece of electronic hardware, the wire slices the electric inventory into that gear, saving it from obliteration. This is what we call a blown circuit.

A blown circuit is not a problem, and changing one doesn’t cost a huge amount of cash. Assuming that your car’s radiator fan is non-functional, look at your car’s client manual and locate the breaker for the radiator fan regulator or the fan.

The actual fan regularly uses a major wire of around 50A, while there may also be a separate small circuit to the fan control module.

Recollect that assuming the fan intertwines is blown – there may be an issue with the wirings or the radiator fan.

Faulty Coolant Temperature Sensor

There are frequently two distinct frameworks in various car models. Either your fan control is integrated into the motor control unit, or you have a separate fan control module.

In the two cases, the control units use a temperature sensor to know when to start the radiator fan.

Assuming this temperature sensor is broken, the control unit won’t know when to start the radiator fan or Cooling Fans Only Work When Temp Sensor Is Unplugged.

While the car is running, unplugging the engine coolant sensor will most likely cause the engine to stumble and run rough. The engine light may not come on right away, but the PCM will log a DTC (Diagnostic Trouble Code).

A few cars use separate motor coolant temperature sensors for the radiator fan and the motor control unit.

You want to check your repair manual for which temperature sensor controls the radiator fan and then resistance-measure the sensor with a multimeter to guarantee it is functional.

Broken Wiring

If the fan is not working when the car is overheating, there may be a wiring issue or a bad association. The radiator fan wiring should be checked from the control unit or relay.

Check in the connector plugs for any indications of erosion. Be sure to also check the connector plugs on the relay and control unit.

Measuring the wirings with a multimeter is regularly not exceptionally viable, as you want to place a load on the wires to check whether they are functional.

As a fast test, you can check with a multimeter assuming power is coming to the radiator fan.

Lacking Coolant

Assuming your coolant level is low, you will get air in the framework, and the coolant temperature sensor won’t read the coolant temperature accurately.

If the coolant level is low, you want to top off the coolant to ideal levels. Failing to do could risk your motor becoming overheated and seized.

There is no approach back from a held onto motor except if you will burn through a truckload of cash.

Broken Radiator Fan

Faulty radiator fans can also cause your radiator fans not to come on. The radiator fans have electrical engines within them, which will wear out after certain years.

You can test the electrical radiator fans by taking a wire from the car battery, turning off the radiator fan connector, and putting 12v+ and ground into the connector.

Testing your radiator fans in this way is fast and simple.

Faulty Fan Relay

Because the radiator fan is frequently drawing such a lot of force, there is regularly a relay driving the coolant fan.

This relay can get damaged, which will cause the radiator fan to not come on. The fan relay is regularly in the motor bay’s circuit box, yet the most effective way is to look at your repair manual to observe where it is located.

Testing a 4-pin relay is frequently exceptionally straightforward. Eliminate the relay and give 12 volts to stick 30 and 85.

Ground pin 86 and look at the off chance that there is voltage coming from pin 87. It is shockingly better to associate pin 87 with something that draws a ton of force, similar to the fan, for example.

Bad Fan Controller Module

A few cars have a separate control module for simply the radiator fan control. This control module is frequently installed in the motor bay, and presented to heat and residue. This can make the control module fail after some time because of consumption.

Locate the relay and check for any visual damages outside of it. You can regularly also open up the relay and check for any bad soldering or erosion. Replace it on the off chance that you see any issues.


In this article, we discussed all that you want to know when you are having an issue with the radiator fan not working.

We shared all the indications related to this and their legitimate fixes. Also, now you know when a Cooling Fans Only Work When Temp Sensor Is Unplugged.

If you have a radiator fan not working, then it’s an ideal opportunity to make an appointment with your mechanic to see what’s the matter with it.

You may pay some cash, however, over the long haul, you will save much more. Imagine assuming that your motor overheats and explodes? You don’t want that thing to happen to you.

Assuming that you run a classic, it is also really smart to see the aftermarket offering and get an advanced cooling framework.

It will be significantly better compared to those old frameworks that were made back in the day.

Frequently Asked Questions

Can a bad temperature sensor cause fan not to work?

A messed-up coolant temperature sensor can also make the radiator fan not function as well. When this sensor fails, it may cause overheating simultaneously. This sensor may also relate to other various manifestations.

Can a car have without a coolant fever sensor?

If you turn off the sensor when the motor is cold, the motor may run as expected from the outset. However, as the motor warms up, the a/f blend will be too rich and the motor will start misfiring and potentially stall.

Does the temperature sensor turn on the fan?

The temperature that’s being emitted by the thermostat is what the sensor works on. The onboard control framework gets the temperature. The cooling fan may be turned on or off when the control framework gets the temperature from the CTS.

2 thoughts on “Cooling Fans Only Work When Temp Sensor Is Unplugged”

  1. I have tried 3 times to troubleshoot my cooling fans, i just dont know what to do. relays seem good i even switched them out from another area that i know work. fuses seem good. coolant levels are good. fan motors run, checked wiring all the way as to even removing fuse box to look for anything wrong and found nothing. changed coolant temp sensor twice. Im going to wire a new connector because the factory one is broken, could my thermostat be faulty and in the stuck position to affect this issue.. This is a LT Traverse 2012. what the hel am i missing, please help before i have my first drink man………………………..PS i rebuilt the whole cooling system 2months ago, new radiator, new water pump, new thermostat and housing and all new coolant hoses……

    • Hi Michael, it sounds like you have already checked a lot of things related to your cooling fans, including relays, fuses, coolant levels, fan motors, wiring, and even the coolant temperature sensor. Since you have also rebuilt the whole cooling system recently, it’s possible that the thermostat could be faulty and stuck in a closed position, which could affect the cooling fans. Wiring a new connector is a good idea, but if that doesn’t solve the issue, I would recommend having a qualified mechanic perform further diagnosis to determine the root cause of the problem.


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