Why is the radiator fan not working on my Lexus LS400?

Possible Reasons for Radiator Fan Not Working on Lexus LS400
There are several potential reasons why the radiator fan may not be working on a Lexus LS400. Some of the common issues include:
1. Faulty Fan Motor: The problem could be caused by a bad cooling fan motor, which may need to be replaced.
2. Coolant Temperature Sensor: Another possible cause is a malfunctioning coolant temperature sensor. This sensor is responsible for activating the fan when the engine reaches a certain temperature.
3. Relay Issues: Problems with the fan relays, such as FAN relay #1 and FAN relay #2, could prevent the fans from turning on.
4. Fuse Problems: A blown fuse, such as the 30A RDI FAN fuse located in the fuse box by the battery, could also be the culprit.
5. Viscous Fan Hub: If the vehicle has a viscous fan hub, it may need to be replaced if it’s not driving the fan hard enough to suck air through the radiator when the car is stationary.
Troubleshooting Steps
If you’re experiencing issues with the radiator fan not working on your Lexus LS400, here are some troubleshooting steps you can take:
1. Check Fan Operation with A/C: Verify if the radiator cooling fan operates when the A/C is turned on. The cooling fan should run at all times when the A/C is on. If it doesn’t, this could indicate a problem with the fan motor.
2. Inspect Coolant Temperature Sensor: Ensure that the coolant temperature sensor, located on the radiator, is functioning properly. This sensor plays a crucial role in activating the fan when the engine reaches a specific temperature.
3. Examine Relays and Fuses: Check the fan relays and fuses, including FAN relay #1, FAN relay #2, and the 30A RDI FAN fuse, to determine if any of these components are causing the issue.
4. Professional Diagnosis: If the above steps do not resolve the issue, it may be necessary to seek professional assistance to diagnose and address the problem effectively.
It’s important to address the radiator fan issue promptly to prevent potential overheating problems in the vehicle.

What sensor turns on the radiator fan?

Yes, the coolant temperature sensor is an important component in controlling the radiator fan in many modern vehicles. The coolant temperature sensor monitors the temperature of the engine coolant and sends this information to the engine control module (ECM), which uses it to determine when to turn on the radiator fan.

Should radiator fan turn on when AC is on?

First, run the AC and see if the radiator fan runs: it’s supposed to run with the AC by default. If it doesn’t run, you likely have a low level of refrigerant in the system or a faulty switch or a sensor, or a bad fan motor, fuse, relay, or a wiring problem.

How do I know if my radiator fan fuse is blown?

You might see a temperature light pop up on your dashboard. In this case stop driving immediately. And turn off your car. The fifth symptom is a blown cooling fan fuse.

How do I know if my fan relay is bad?

If the cooling fan relay has failed, you may see warnings, such as the check engine light and the temperature warning light, pop up on the dash, but first, you may notice that the A/C stops cooling.

How do I know if my car fan relay is bad?

If the cooling fan relay has failed, you may see warnings, such as the check engine light and the temperature warning light, pop up on the dash, but first, you may notice that the A/C stops cooling.

How do I know if my fan relay is blown?

If your car has these symptoms, you should check the fan relay:

1. your engine overheats;
2. the fans don’t start;
3. your air conditioner does not work well or does not work at all;
4. the fan doesn’t turn off.

What activates the radiator fan?

A cooling fan in a car is activated by two means – either by the thermostat in the car’s cooling system, or by an electronic system that senses when the coolant is too hot and switched on the fan through an electrical relay switch.

What stops a radiator fan from working?

A signal from the coolant temperature sensor is what triggers the ECU to turn on the radiator fan, and if it’s faulty, it can prevent the fan from working at all. Test the fan relay. Since the relay operates as a switch for the fan’s power, a defective cooling fan relay won’t energize the circuit.

Where is the fan relay on the ls400?

These relays are in front of the radiator on the driver’s side and behind the headlight. The electrical fan is in front of the radiator.

Why are my radiator fans not kicking on?

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.